Methods and compositions for inhibiting CD32B expressing cells

ABSTRACT

The present invention relates to immunoglobulins that bind FcγRIIb+ cells and coengage the antigen on the cell&#39;s surface and an FcγRIIb on the cell&#39;s surface, methods for their generation, and methods for using the immunoglobulins.

RELATED APPLICATIONS

This application claims benefit under 35 U.S.C §120 to U.S. applicationSer. No. 12/156,183 (filed May 30, 2008); which claims benefit under 35U.S.C § 119 (e) to U.S. Provisional Application Nos. 60/940,776 (filedMay 30, 2007); 60/953,174 (filed Jul. 31, 2007); 60/970,413 (filed Sep.6, 2007); 60/976,279 (filed Sep. 28, 2007); 60/990,509 (filed Nov. 27,2007); 61/012,035 (filed Dec. 6, 2007); 61/013,775 (filed Dec. 14,2007), 61/019,395 (filed Jan. 7, 2008), 61/032,059 (filed Feb. 27,2008), 61/043,585 (filed Apr. 9, 2008), and 61/046,397 (filed Apr. 18,2008). Each of the above applications is incorporated in its entirety byreference.

SEQUENCE LISTING

A Sequence Listing submitted in computer readable form (CRF) is herebyincorporated by reference.

TECHNICAL FIELD

The present disclosure relates to methods of inhibiting cells thatexpress the Fc gamma receptor CD32b (FcγRIIb), immunoglobulincompositions that may be useful for such methods, and application ofsuch compositions for treating immune disorders and hematologicalmalignancies.

BACKGROUND

Antigen recognition by B cells is mediated by the B cell receptor (BCR),a surface-bound immunoglobulin in complex with signaling componentsCD79a (Igα) and CD79b (Igβ). Crosslinking of BCR upon engagement ofantigen results in phosphorylation of immunoreceptor tyrosine-basedactivation motifs (ITAMs) within CD79a and CD79b, initiating a cascadeof intracellular signaling events that recruit downstream molecules tothe membrane and stimulate calcium mobilization. This leads to theinduction of diverse B cell responses (e.g., cell survival,proliferation, antibody production, antigen presentation,differentiation, etc.) which lead to a humoral immune response(DeFranco, A. L., 1997, Curr. Opin. Immunol. 9, 296-308; Pierce, S. K.,2002, Nat. Rev. Immunol. 2, 96-105; Ravetch, J. V. & Lanier, L. L.,2000, Science 290, 84-89). Other components of the BCR coreceptorcomplex enhance (e.g., CD19, CD21, and CD81) or suppress (e.g., CD22 andCD72) BCR activation signals (Doody, G. M. et al., 1996, Curr. Opin.Immunol. 8, 378-382; Li, D. H. et al., 2006, J. Immunol. 176,5321-5328). In this way, the immune system maintains multiple BCRregulatory mechanisms to ensure that B cell responses are tightlycontrolled.

When antibodies are produced to an antigen, the circulating level ofimmune complexes (e.g., antigen bound to antibody) increases. Theseimmune complexes downregulate antigen-induced B cell activation. It isbelieved that these immune complexes downregulate antigen-induced B cellactivation by coengaging cognate BCR with the low-affinity inhibitoryreceptor FcγRIIb, the only IgG receptor on B cells (Heyman, B., 2003,Immunol. Lett. 88, 157-161). It is also believed that this negativefeedback of antibody production requires interaction of the antibody Fcdomain with FcγRIIb since immune complexes containing F(ab′)₂ antibodyfragments are not inhibitory (Chan, P. L. & Sinclair, N. R., 1973,Immunology 24, 289-301). The intracellular immunoreceptor tyrosine-basedinhibitory motif (ITIM) of FcγRIIb is necessary to inhibit BCR-inducedintracellular signals (Amigorena, S. et al., 1992, Science 256,1808-1812; Muta, T., et al., 1994, Nature 368, 70-73). This inhibitoryeffect occurs through phosphorylation of the FcγRIIb ITIM, whichrecruits SH2-containing inositol polyphosphate 5-phosphatase (SHIP) toneutralize ITAM-induced intracellular calcium mobilization (Kiener, P.A., et al., 1997, J. Biol. Chem. 272, 3838-3844; Ono, M., et al., 1996,Nature 383, 263-266; Ravetch, J. V. & Lanier, L. L., 2000, Science 290,84-89). In addition, FcγRIIb-mediated SHIP phosphorylation inhibits thedownstream Ras-MAPK proliferation pathway (Tridandapani, S. et al.,1998, Immunol. 35, 1135-1146).

SUMMARY OF EXEMPLARY EMBODIMENTS

The present disclosure provides novel immunoglobulins, compositionscomprising such immunoglobulins, and methods of using the immunoglobulinto inhibit cells that express FcγRIIb. The FcγRIIb⁺ cell inhibitorymethods disclosed herein comprise contacting FcγRIIb⁺ cells with animmunoglobulin that binds FcγRIIb and coengages a target antigen on thecell's surface and an FcγRIIb on the cell's surface. In one embodiment,the immunoglobulin binds with FcγRIIb, wherein the affinity of saidbinding has a Kd less than about 100 nM, e.g., less than or equal toabout 95 nM, less than or equal to about 90 nM, less than or equal toabout 85 nM, less than or equal to about 80 nM, less than or equal toabout 75 nM, less than or equal to about 74 nM. In one embodiment, theimmunoglobulin comprises an Fc region, wherein said Fc region comprisesone or more modifications compared to a parent Fc region, wherein saidmodifications are at positions selected from the group consisting of234, 235, 236, 237, 239, 265, 266, 267, 268, 298, 325, 326, 327, 328,329, 330, 331, and 332, wherein numbering is according to the EU index.In another embodiment, the immunoglobulin is a bispecific antibodycomprising a first Fv region and a second Fv region, wherein said firstFv region binds the target antigen, and said second Fv region bindsFcγRIIb with a Kd of less than about 100 nM. In another embodiment, theimmunoglobulin is an Fc fusion comprising an Fc region, wherein said Fcregion binds FcγRIIb with a Kd of less than about 100 nM. FcγRIIb⁺ cellsas disclosed herein may be cancer cells, B cells, plasma cells,dendritic cells, macrophages, neutrophils, mast cells, basophils,eosinophils, and a combination thereof.

Also disclosed herein are novel methods of inhibiting activation of Bcells. The B cell inhibitory methods disclosed herein comprisecontacting B cells with an immunoglobulin that binds FcγRIIb andcoengages a target antigen on the B cell's surface and an FcγRIIb on theB cell's surface. In one embodiment, the immunoglobulin binds withFcγRIIb, wherein the affinity of said binding has a Kd less than about100 nM, e.g., less than or equal to about 95 nM, less than or equal toabout 90 nM, less than or equal to about 85 nM, less than or equal toabout 80 nM, less than or equal to about 75 nM, less than or equal toabout 74 nM. In one embodiment, the immunoglobulin comprises an Fcregion, wherein said Fc region comprises one or more modificationscompared to a parent Fc region, wherein said modifications are atpositions selected from the group consisting of 234, 235, 236, 237, 239,265, 266, 267, 268, 298, 325, 326, 327, 328, 329, 330, 331, and 332,wherein numbering is according to the EU index. In another embodiment,the immunoglobulin is a bispecific antibody comprising a first Fv regionand a second Fv region, wherein said first Fv region binds the targetantigen, and said second Fv region binds FcγRIIb with a Kd of less thanabout 100 nM. In another embodiment, the immunoglobulin is an Fc fusioncomprising an Fc region, wherein said Fc region binds FcγRIIb with a Kdof less than about 100 nM. In one embodiment, the immunoglobulin bindsat least two B cell proteins, e.g., at least two proteins bound, or thatmay be bound, on the surface of B cells. In one embodiment, the first ofsaid B cell proteins is FcγRIIb and the second of said B cell proteinsis part of the B cell receptor (BCR) complex. In another embodiment, thesecond of said B cell proteins is not involved directly in antigenrecognition. In another embodiment, the second of said B cell proteinsis an antigen bound to the BCR complex. In some embodiments, theimmunoglobulins inhibit release of calcium from the B cells upon theirstimulation through the B cell receptor. In another embodiment, animmunoglobulin disclosed herein binds at least two B cell proteins boundon the surface of the same B cell.

Also disclosed herein are novel methods of treating B cell-mediateddisorders, e.g., autoimmune diseases, inflammatory diseases,hematological malignancies, etc. The treatment methods disclosed hereincomprise administration to a patient in need of such administration atherapeutic amount of an immunoglobulin that binds FcγRIIb⁺ cells andcoengages a target antigen on the cell's surface and an FcγRIIb oncell's surface. In one embodiment, the immunoglobulin binds withFcγRIIb, wherein the affinity of said binding has a Kd less than about100 nM, e.g., less than or equal to about 95 nM, less than or equal toabout 90 nM, less than or equal to about 85 nM, less than or equal toabout 80 nM, less than or equal to about 75 nM, less than or equal toabout 74 nM. In one embodiment, the immunoglobulin comprises an Fcregion, wherein said Fc region comprises one or more modificationscompared to a parent Fc region, wherein said modifications are atpositions selected from the group consisting of 234, 235, 236, 237, 239,265, 266, 267, 268, 298, 325, 326, 327, 328, 329, 330, 331, and 332,wherein numbering is according to the EU index. In another embodiment,the immunoglobulin is a bispecific antibody comprising a first Fv regionand a second Fv region, wherein said first Fv region binds the targetantigen, and said second Fv region binds FcγRIIb with a Kd of less thanabout 100 nM. In another embodiment, the immunoglobulin is an Fc fusioncomprising an Fc region, wherein said Fc region binds FcγRIIb with a Kdof less than about 100 nM. In some embodiments, autoimmune andinflammatory diseases that may be treated by the methods disclosedherein include Systemic Lupus Erythematosus, Rheumatoid arthritis,Sjogren's syndrome, Multiple sclerosis, Idiopathic thrombocytopenicpurpura (ITP), Graves disease, Inflammatory bowel disease, Psoriasis,Type I diabetes, and Asthma.

Disclosed herein are novel FcγRIIb+ cell inhibitory immunoglobulincompositions. The compositions disclosed herein include immunoglobulinsthat bind FcγRIIb+ cells and coengage a target antigen on the cell'ssurface and an FcγRIIb on cell's surface. In one embodiment, theimmunoglobulin binds with FcγRIIb, wherein the affinity of said bindinghas a Kd less than about 100 nM, e.g., less than or equal to about 95nM, less than or equal to about 90 nM, less than or equal to about 85nM, less than or equal to about 80 nM, less than or equal to about 75nM, less than or equal to about 74 nM. In one embodiment, theimmunoglobulin comprises an Fc region, wherein said Fc region comprisesone or more modifications compared to a parent Fc region, wherein saidmodifications are at positions selected from the group consisting of234, 235, 236, 237, 239, 265, 266, 267, 268, 298, 325, 326, 327, 328,329, 330, 331, and 332, wherein numbering is according to the EU index.In another embodiment, the immunoglobulin is a bispecific antibodycomprising a first Fv region and a second Fv region, wherein said firstFv region binds the target antigen, and said second Fv region bindsFcγRIIb with a Kd of less than about 100 nM. In another embodiment, theimmunoglobulin is an Fc fusion comprising an Fc region, wherein said Fcregion binds FcγRIIb with a Kd of less than about 100 nM.

In some embodiments, the immunoglobulins that bind FcγRIIb+ cells andcoengage a target antigen on the cell's surface and an FcγRIIb on cell'ssurface disclosed herein may bind and/or coengage a target antigenselected from the group consisting of: CD19, CD20, CD21 (CR2), CD22,CD23/FcεRII, FcεRI, (α, β, and γ subunits), CD24/BBA-1/HSA, CD27, CD35(CR1), CD38, CD40, CD45RA, CD52/CAMPATH-1/HE5, CD72, CD79a (Igα), CD79b(Igβ), IgM (μ), CD80, CD81, CD86, Leu13, HLA-DR, -DP, -DQ, CD138,CD317/HM1.24, CD11a, CD11b, CD11c, CD14, CD68, CD163, CD172a, CD200R,and CD206. In other embodiments, the immunoglobulins that bind FcγRIIb+cells and coengage a target antigen on the cell's surface and an FcγRIIbon cell's surface disclosed herein may bind and/or coengage a targetantigen selected from the group consisting of: IgM (μ), CD19, CD20,CD21, CD22, CD23, CD24, CD35, CD40, CD45RA, CD72, CD79a, CD79b, CD80,CD81, CD86, and HLA-DR. In one embodiment, immunoglobulins that bindFcγRIIb+ cells and coengage a target antigen on the cell's surface andan FcγRIIb on cell's surface disclosed herein may bind and/or coengage atarget antigen selected from the group consisting of: IgM (μ), CD79a,CD79b, CD19, CD21, CD22, CD72, CD81, and Leu13. In one embodiment,immunoglobulins that bind FcγRIIb+ cells and coengage a target antigenon the cell's surface and an FcγRIIb on cell's surface disclosed hereinmay bind and/or coengage a target antigen selected from the groupconsisting of: IgM (μ), CD19, CD79a, CD79b, CD81, and HLA-DR. In anotherembodiment, immunoglobulins that bind FcγRIIb+ cells and coengage atarget antigen on the cell's surface and an FcγRIIb on cell's surfacedisclosed herein may bind and/or coengage a target antigen selected fromthe group consisting of: CD22, CD40, and CD72.

In one embodiment, the immunoglobulins that bind FcγRIIb+ cells andcoengage a target antigen on the cell's surface and an FcγRIIb on cell'ssurface disclosed herein may bind and/or coengage an autoantigen orallergen. In an alternate embodiment, an immunoglobulin disclosed hereinmay be an Fc fusion that is covalently linked to an autoantigen orallergen. In one embodiment, the autoantigen is selected from the groupconsisting citrullinated proteins and peptides such as CCP-1, CCP-2(cyclical citrullinated peptides), fibrinogen, fibrin, vimentin,fillaggrin, collagen I and II peptides, alpha-enolase, translationinitiation factor 4G1, perinuclear factor, keratin, Sa (cytoskeletalprotein vimentin), components of articular cartilage such as collagenII, IX, and XI, circulating serum proteins such as RFs (IgG, IgM),fibrinogen, plasminogen, ferritin, nuclear components such as RA33/hnRNPA2, Sm, eukaryotic trasnlation elogation factor 1 alpha 1, stressproteins such as HSP-65, -70, -90, BiP, inflammatory/immune factors suchas B7-H1, IL-1 alpha, and IL-8, enzymes such as calpastatin,alpha-enolase, aldolase-A, dipeptidyl peptidase, osteopontin,glucose-6-phosphate isomerase, receptors such as lipocortin 1,neutrophil nuclear proteins such as lactoferrin and 25-35kD nuclearprotein, granular proteins such as bactericidal permeability increasingprotein (BPI), elastase, cathepsin G, myeloperoxidase, proteinase 3,platelet antigens, myelin protein antigen, islet cell antigen,rheumatoid factor, histones, ribosomal P proteins, cardiolipin,vimentin, nucleic acids such as dsDNA, ssDNA, and RNA, ribonuclearparticles and proteins such as Sm antigens (including but not limited toSmD's and SmB′/B), U1RNP, A2/B1 hnRNP, Ro (SSA), and La (SSB) antigens.

In one embodiment, immunoglobulins that bind FcγRIIb+ cells and coengagea target antigen on the cell's surface and an FcγRIIb on cell's surfacedisclosed herein may be variant immunoglobulins relative to a parentimmunoglobulin. In one embodiment, the variant immunoglobulin comprisesa variant Fc region, wherein said variant Fc region comprises one ormore (e.g., two or more) modification(s) compared to a parent Fc region,wherein said modification(s) are at positions selected from the groupconsisting of 234, 235, 236, 237, 239, 265, 266, 267, 268, 298, 325,326, 327, 328, 329, 330, 331, and 332, wherein numbering is according tothe EU index. In one embodiment, the variant immunoglobulin comprises avariant Fc region, wherein said variant Fc region comprises one or more(e.g., two or more) modification(s) compared to a parent Fc region,wherein said modification(s) are at positions selected from the groupconsisting of 234, 235, 236, 237, 239, 266, 267, 268, 325, 326, 327,328, and 332, according to the EU index. In one embodiment, the variantimmunoglobulin comprises a variant Fc region, wherein said variant Fcregion comprises one or more (e.g., two or more) modification(s)compared to a parent Fc region, wherein said modification(s) are atpositions selected from the group consisting of 234, 235, 236, 237, 266,267, 268, 327, 328, according to the EU index. In one embodiment, thevariant immunoglobulin comprises a variant Fc region, wherein saidvariant Fc region comprises one or more (e.g., two or more)modification(s) compared to a parent Fc region, wherein saidmodification(s) are at positions selected from the group consisting of235, 236, 266, 267, 268, 328, according to the EU index. In oneembodiment, the variant immunoglobulin comprises a variant Fc region,wherein said variant Fc region comprises one or more (e.g., two or more)modification(s) compared to a parent Fc region, wherein saidmodification(s) are at positions selected from the group consisting of235, 236, 239, 266, 267, 268, and 328, according to the EU index. In oneembodiment, the variant immunoglobulin comprises a variant Fc region,wherein said variant Fc region comprises one or more (e.g., two or more)modification(s) compared to a parent Fc region, wherein saidmodification(s) are at positions selected from the group consisting of234, 235, 236, 237, 266, 267, 268, 327, 328, according to the EU index

In one embodiment, said modification(s) is at least one substitution(e.g., one or more substitution(s), two or more substitution(s), etc.)selected from the group consisting of 234F, 234G, 234I, 234K, 234N,234P, 234Q, 234S, 234V, 234W, 234Y, 234D, 234E, 235A, 235E, 235H, 235I,235N, 235P, 235Q, 235R, 235S, 235W, 235Y, 235D, 235F, 235T, 236D, 236F,236H, 236I, 236K, 236L, 236M, 236P, 236Q, 236R, 236S, 236T, 236V, 236W,236Y, 236A, 236E, 236N, 237A, 237E, 237H, 237K, 237L, 237P, 237Q, 237S,237V, 237Y, 237D, 237N, 239D, 239E, 239N, 239Q, 265E, 266D, 266I, 266M,267A, 267D, 267E, 267G, 268D, 268E, 268N, 268Q, 298D, 298E, 298L, 298M,298Q, 325L, 326A, 326E, 326W, 326D, 327D, 327G, 327L, 327N, 327Q, 327E,328E, 328F, 328Y, 328H, 328I, 328Q, 328W, 329E, 330D, 330H, 330K, 330S,331S, and 332E, wherein numbering is according to an EU index. In oneembodiment, said modification(s) is at least one substitution (e.g., oneor more substitution(s), two or more substitution(s), etc.) selectedfrom the group consisting of 234N, 234F, 234D, 234E, 234W, 235Q, 235R,235W, 235Y, 235D, 235F, 235T, 236D, 236H, 236I, 236L, 236S, 236Y, 236E,236N, 237H, 237L, 237D, 237N, 239D, 239N, 239E, 266I, 266M, 267A, 267D,267E, 267G, 268D, 268E, 268N, 268Q, 298E, 298L, 298M, 298Q, 325L, 326A,326E, 326W, 326D, 327D, 327L, 327E, 328E, 328F, 328Y, 328H, 328I, 328Q,328W, 330D, 330H, 330K, and 332E, wherein numbering is according to anEU index. In one embodiment, said modification(s) is at least onesubstitution (e.g., one or more substitution(s), two or moresubstitution(s), etc.) selected from the group consisting of 234D, 234E,234W, 235D, 235F, 235R, 235Y, 236D, 236N, 237D, 237N, 239D, 239E, 266M,267D, 267E, 268D, 268E, 327D, 327E, 328F, 328W, 328Y, and 332E, whereinnumbering is according to an EU index. In one embodiment, saidmodification(s) is at least one substitution (e.g., one or moresubstitution(s), two or more substitution(s), etc.) selected from thegroup consisting of L234E, L235Y, L235R, G236D, G236N, G237N, V266M,S267E, H268E, H268D, A327D, A327E, L328F, L328Y, L328W, whereinnumbering is according to an EU index. In one embodiment, saidmodification(s) is at least one substitution (e.g., one or moresubstitution(s), two or more substitution(s), etc.) selected from thegroup consisting of 235Y, 236D, 239D, 266M, 267E, 268D, 268E, 328F,328W, and 328Y, wherein numbering is according to an EU index. In oneembodiment, said modification(s) is at least one substitution (e.g., oneor more substitution(s), two or more substitution(s), etc.) selectedfrom the group consisting of L235Y, G236D, V266M, S267E, H268E, H268D,L328F, L328Y, and L328W, wherein numbering is according to an EU index.

In one embodiment, said modification(s) is at least two modifications(e.g., a combination of modifications) at positions selected from thegroup consisting of 234/239, 234/267, 234/328, 235/236, 235/239,235/267, 235/268, 235/328, 236/239, 236/267, 236/268, 236/328, 237/267,239/267, 239/268, 239/327, 239/328, 239/332, 266/267, 267/268, 267/325,267/327, 267/328, 267/332, 268/327, 268/328, 268/332, 326/328, 327/328,and 328/332, wherein numbering is according to an EU index. In oneembodiment, said modification(s) is at least two modifications (e.g., acombination of modifications) at positions selected from the groupconsisting of 235/267, 236/267, 239/268, 239/267, 267/268, and 267/328,wherein numbering is according to an EU index. In one embodiment, saidmodification(s) is at least two substitutions (e.g., a combination ofsubstitutions) selected from the group consisting of 234D/267E,234E/267E, 234F/267E, 234E/328F, 234W/239D, 234W/239E, 234W/267E,234W/328Y, 235D/267E, 235D/328F, 235F/239D, 235F/267E, 235F/328Y,235Y/236D, 235Y/239D, 235Y/267D, 235Y/267E, 235Y/268E, 235Y/328F,236D/239D, 236D/267E, 236D/268E, 236D/328F, 236N/267E, 237D/267E,237N/267E, 239D/267D, 239D/267E, 239D/268D, 239D/268E, 239D/327D,239D/328F, 239D/328W, 239D/328Y, 239D/332E, 239E/267E, 266M/267E,267D/268E, 267E/268D, 267E/268E, 267E/325L, 267E/327D, 267E/327E,267E/328F, 267E/328I, 267E/328Y, 267E/332E, 268D/327D, 268D/328F,268D/328W, 268D/328Y, 268D/332E, 268E/328F, 268E/328Y, 327D/328Y,328F/332E, 328W/332E, and 328Y/332E, wherein numbering is according toan EU index.

In one embodiment, said modification(s) result in at least one of thefollowing substitutions, or combinations of substitutions: 234F/236N,234F/236D, 236A/237A, 236S/237A, 235D/239D, 234D/267E, 234E/267E,234F/267E, 235D/267E, 235F/267E, 235S/267E, 235T/267E, 235Y/267D,235Y/267E, 236D/267E, 236E/267E, 236N/267E, 237D/267E, 237N/267E,239D/267D, 239D/267E, 266M/267E, 234E/268D, 236D/268D, 239D/268D,267D/268D, 267D/268E, 267E/268D, 267E/268E, 267E/325L, 267D/327D,267D/327E, 267E/327D, 267E/327E, 268D/327D, 239D/328Y, 267E/328F,267E/328H, 267E/328I, 267E/328Q, 267E/328Y, 268D/328Y, 239D/332E,328Y/332E, 234D/236N/267E, 235Y/236D/267E, 234W/239E/267E,235Y/239D/267E, 236D/239D/267E, 235Y/267E/268E, 236D/267E/268E,239D/267E/268E, 234W/239D/328Y, 235F/239D/328Y, 234E/267E/328F,235D/267E/328F, 235Y/267E/328F, 236D/267E/328F, 239D/267A/328Y,239D/267E/328F, 234W/268D/328Y, 235F/268D/328Y, 239D/268D/328F,239D/268D/328W, 239D/268D/328Y, 239D/268E/328Y, 267A/268D/328Y,267E/268E/328F, 239D/326D/328Y, 268D/326D/328Y, 239D/327D/328Y,268D/327D/328Y, 239D/267E/332E, 234W/328Y/332E, 235F/328Y/332E,239D/328F/332E, 239D/328Y/332E, 267A/328Y/332E, 268D/328F/332E,268D/328W/332E, 268D/328Y/332E, 268E/328Y/332E, 326D/328Y/332E,327D/328Y/332E, 234W/236D/239E/267E, 239D/268D/328F/332E,239D/268D/328W/332E, and 239D/268D/328Y/332E, wherein numbering isaccording to an EU index. In one embodiment, said modification(s) resultin at least one of the following substitutions, or combinations ofsubstitutions: 266D, 234F/236N, 234F/236D, 236A/237A, 236S/237A,235D/239D, 234D/267E, 234E/267E, 234F/267E, 235D/267E, 235F/267E,235S/267E, 235T/267E, 235Y/267D, 236D/267E, 236E/267E, 236N/267E,237D/267E, 237N/267E, 266M/267E, 234E/268D, 236D/268D, 267D/268D,267D/268E, 267E/268D, 267E/268E, 267E/325L, 267D/327D, 267D/327E,267E/327E, 268D/327D, 239D/328Y, 267E/328F, 267E/328H, 267E/328I,267E/328Q, 267E/328Y, 268D/328Y, 234D/236N/267E, 235Y/236D/267E,234W/239E/267E, 235Y/239D/267E, 236D/239D/267E, 235Y/267E/268E,236D/267E/268E, 234W/239D/328Y, 235F/239D/328Y, 234E/267E/328F,235D/267E/328F, 235Y/267E/328F, 236D/267E/328F, 239D/267A/328Y,239D/267E/328F, 234W/268D/328Y, 235F/268D/328Y, 239D/268D/328F,239D/268D/328W, 239D/268D/328Y, 239D/268E/328Y, 267A/268D/328Y,267E/268E/328F, 239D/326D/328Y, 268D/326D/328Y, 239D/327D/328Y,268D/327D/328Y, 234W/328Y/332E, 235F/328Y/332E, 239D/328F/332E,239D/328Y/332E, 267A/328Y/332E, 268D/328F/332E, 268D/328W/332E,268D/328Y/332E, 268E/328Y/332E, 326D/328Y/332E, 327D/328Y/332E,234W/236D/239E/267E, 239D/268D/328F/332E, 239D/268D/328W/332E, and239D/268D/328Y/332E, wherein numbering is according to an EU index. Inone embodiment, said modification(s) result in at least one of thefollowing substitutions, or combinations of substitutions: 234N, 235Q,235R, 235W, 235Y, 236D, 236H, 236I, 236L, 236S, 236Y, 237H, 237L, 239D,239N, 266I, 266M, 267A, 267D, 267E, 267G, 268D, 268E, 268N, 268Q, 298E,298L, 298M, 298Q, 326A, 326E, 326W, 327D, 327L, 328E, 328F, 330D, 330H,330K, 234F/236N, 234F/236D, 235D/239D, 234D/267E, 234E/267E, 234F/267E,235D/267E, 235F/267E, 235T/267E, 235Y/267D, 235Y/267E, 236D/267E,236E/267E, 236N/267E, 237D/267E, 237N/267E, 239D/267D, 239D/267E,266M/267E, 234E/268D, 236D/268D, 239D/268D, 267D/268D, 267D/268E,267E/268D, 267E/268E, 267E/325L, 267D/327D, 267D/327E, 267E/327D,267E/327E, 268D/327D, 239D/328Y, 267E/328F, 267E/328H, 267E/328I,267E/328Q, 267E/328Y, 268D/328Y, 239D/332E, 328Y/332E, 234D/236N/267E,235Y/236D/267E, 234W/239E/267E, 235Y/239D/267E, 236D/239D/267E,235Y/267E/268E, 236D/267E/268E, 239D/267E/268E, 234W/239D/328Y,235F/239D/328Y, 234E/267E/328F, 235D/267E/328F, 235Y/267E/328F,236D/267E/328F, 239D/267A/328Y, 239D/267E/328F, 234W/268D/328Y,235F/268D/328Y, 239D/268D/328F, 239D/268D/328W, 239D/268D/328Y,239D/268E/328Y, 267A/268D/328Y, 267E/268E/328F, 239D/326D/328Y,268D/326D/328Y, 239D/327D/328Y, 268D/327D/328Y, 239D/267E/332E,234W/328Y/332E, 235F/328Y/332E, 239D/328F/332E, 239D/328Y/332E,267A/328Y/332E, 268D/328F/332E, 268D/328W/332E, 268D/328Y/332E,268E/328Y/332E, 326D/328Y/332E, 327D/328Y/332E, 234W/236D/239E/267E,239D/268D/328F/332E, 239D/268D/328W/332E, and 239D/268D/328Y/332E

In one embodiment, said modification(s) result in at least one of thefollowing substitutions, or combinations of substitutions: 235Y/267E,236D/267E, 239D/268D, 239D/267E, 267E/268D, 267E/268E, and 267E/328F,wherein numbering is according to an EU index.

In one embodiment, the modifications disclosed herein reduce affinity toat least one receptor relative to the parent immunoglobulin, whereinsaid receptor is selected from the group consisting of FcγRI, FcγRIIa,and FcγRIIIa. In an alternate embodiment, immunoglobulin variantsdisclosed herein mediate reduced ADCC or ADCP relative to the parentimmunoglobulin.

Also disclosed herein are methods for engineering the novelimmunoglobulin compositions.

Also disclosed herein are methods for screening target antigens fortheir capacity to mediate cellular inhibition via an FcγRIIb-dependentmechanism. In one embodiment, the antigen screening methods disclosedherein comprise the step of binding a cell that expresses the targetantigen and FcγRIIb with an immunoglobulin that binds with enhancedaffinity, e.g., the Kd of the immunoglobulin may be less than about 100nM to at least FcγRIIb. In another embodiment, simultaneous binding ofboth target antigen and FcγRIIb by the immunoglobulin results in aninhibitory cellular response. In one embodiment of the screening methodsdisclosed herein, the cell is selected from the group consisting of: Bcells, plasma cells, dendritic cells, macrophages, neutrophils, mastcells, basophils, or eosinophils. In another some screening methodsdisclosed herein, the immunoglobulin may be specific for the targetantigen. In an alternate embodiment, immunoglobulin is specific for anantibody, wherein said antibody is specific for the target antigen. Inan alternate embodiment, the immunoglobulin is specific for a hapten,and wherein either the target antigen, or an antibody or protein that isspecific for the target antigen is haptenized.

Also disclosed herein are isolated nucleic acids encoding theimmunoglobulins described herein. Also disclosed herein are vectorscomprising the nucleic acids, optionally, operably linked to controlsequences. Also disclosed herein are host cells containing the vectors,and methods for producing and optionally recovering the immunoglobulincompositions.

Also disclosed herein are immunoglobulin polypeptides, that comprise theimmunoglobulins disclosed herein. The immunoglobulin polypeptides mayfind use in a therapeutic product. In one embodiment, the immunoglobulinpolypeptides disclosed herein may be antibodies.

Also disclosed are compositions comprising immunoglobulin polypeptidesdescribed herein, and a physiologically or pharmaceutically acceptablecarrier or diluent.

Also described are therapeutic and diagnostic uses for theimmunoglobulin polypeptides disclosed herein. In one embodiment, theimmunoglobulins disclosed herein are used to treat one or moreautoimmune disease or inflammatory disease. In an alternate embodiment,the immunoglobulins disclosed herein are used to treat one or morehematological malignancies.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B. Alignment of the amino acid sequences of the human IgGimmunoglobulins IgG1, IgG2, IgG3, and IgG4. FIG. 1A provides thesequences of the CH1 (Cγ1) and hinge domains, and FIG. 1B provides thesequences of the CH2 (Cγ2) and CH3 (Cγ3) domains. Positions are numberedaccording to the EU index of the IgG1 sequence, and differences betweenIgG1 and the other immunoglobulins IgG2, IgG3, and IgG4 are shown ingray. Allotypic polymorphisms exist at a number of positions, and thusslight differences between the presented sequences and sequences in theprior art may exist. The possible beginnings of the Fc region arelabeled, defined herein as either EU position 226 or 230.

FIGS. 2A-2B. Common haplotypes of the human gamma1 (FIG. 2A) and gamma2(FIG. 2B) chains.

FIG. 3. Novel methods of inhibiting B cell activation. Here CRrepresents a co-receptor of the BCR complex, but could be any antigenexpressed on any FcγRIIb+ cell.

FIG. 4. FcγR positions that contribute to FcγRIIb and FcγRIIIa bindingselectivity. Positions were identified by evaluating proximity to theFcγR/Fc interface and amino acid dissimilarity between FcγRIIb andFcγRIIIa.

FIG. 5. Fc positions proximal to FcγR positions contributing to FcγRIIband FcγRIIIa binding selectivity, as listed in FIG. 6.

FIG. 6. Biacore surface plasmon resonance sensorgrams showing binding ofFc variant anti-CD19 antibodies to human FcγRIIb.

FIGS. 7A-7D. Affinities of Fc variant antibodies for human FcγRs asdetermined by Biacore surface plasmon resonance. FIG. 7A is a tablelisting the dissociation constant (Kd) for binding anti-CD19 variantantibodies to human FcγRI, FcγRIIa (131R), FcγRIIa (131H), FcγRIIb,FcγRIIIa (158V), and FcγRIIIa (158F). FIG. 7B is a continuation of thelist in FIG. 7A. FIG. 7C is a continuation of the list in FIG. 7A andFIG. 7B. FIG. 7D is a continuation of the list in FIG. 7A, FIG. 7B, andFIG. 7C. Multiple observations have been averaged. n.d.=no detectablebinding.

FIGS. 8A-8D. Fold affinities of Fc variant antibodies for human FcγRs asdetermined by Biacore surface plasmon resonance. FIG. 8A is a tablelisting the fold improvement or reduction in affinity relative to WTIgG1 for binding of anti-CD19 variant antibodies to human FcγRI, FcγRIIa(131R), FcγRIIa (131H), FcγRIIb, FcγRIIIa (158V), and FcγRIIIa (158F).FIG. 8B is a continuation of the list in FIG. 8A. FIG. 8C is acontinuation of the list in FIG. 8A and FIG. 8B. FIG. 8D is acontinuation of the list in FIG. 8A, FIG. 8B, and FIG. 8C.Fold=KD(Native IgG1)/KD(variant). n.d.=no detectable binding.

FIG. 9. Affinities of Fc variant antibodies for human FcγRs asdetermined by Biacore surface plasmon resonance. The graph shows the-log(KD) for binding of anti-CD19 variant and WT IgG1 antibodies tohuman FcγRI (I), R131 FcγRIIa (RIIa), H131 FcγRIIa (HIIa), FcγRIIb(IIb), and V158 FcγRIIIa (VIIIa). Binding of L235Y/S267E, G236D/S267E,and S267E/L328F to V158 FcγRIIIa was not detectable.

FIG. 10. Affinities of Fc variant antibodies for human FcγRs asdetermined by Biacore surface plasmon resonance. The graph shows the-log(KD) for binding of anti-CD19 variant and WT IgG1 antibodies tohuman FcγRI (I), R131 FcγRIIa (RIIa), H131 FcγRIIa (HIIa), FcγRIIb(IIb), and V158 FcγRIIIa (VIIIa).

FIGS. 11A-11E. Analysis of combination variants (doubles, triples) forsynergistic and non-additive effects in binding to human FcγRIIb (FIG.11A), FcγRI (FIG. 11B), R131 FcγRIIa (FIG. 11C), H131 FcγRIIa (FIG.11D), and V158 FcγRIIIa (FIG. 11E). The ratio between actual foldimprovement measured by SPR and expected fold improvement calculated bymultiplying the fold improvements of the single substitution variants isplotted. Ratios greater than one indicate a synergistic effect.

FIG. 12. Binding of Fc variant antibodies to human FcγRs relative to WTIgG1 as measured by cell surface binding. Antibodies (variant and WTIgG1) were added to HEK293T cells transfected with FcγRIIb to assesscell surface binding. The binding curves were constructed by plottingMFI as a function of Fc variant concentration.

FIGS. 13A-13D. Affinities of Fc variant antibodies for mouse andcynologous monkey (Macaca fascicularis) FcγRs as determined by Biacoresurface plasmon resonance, either by dissociation constant (Kd) oroff-rate determination as indicated. FIG. 13A is a table listing thefold improvement relative to WT IgG1 for binding of anti-CD19 antibodyvariants to mouse FcγRI, mouse FcγRII, mouse FcγRIII, mouse FcγRIV,cynomolgus monkey FcγRI, cynomolgus monkey FcγRIIa, cynomolgus monkeyFcγRIIb, and cynomolgus monkey FcγRIIIa. FIG. 13B is a continuation ofthe list in FIG. 13A. FIG. 13C is a continuation of the list in FIG. 13Aand FIG. 13B. FIG. 13D is a continuation of the list in FIG. 13A, FIG.13B, and FIG. 13C. NB=no detectable binding.

FIG. 14. Affinities of Fc variant antibodies for human FcγRs asdetermined by Biacore surface plasmon resonance. The graph shows the-log(KD) for binding of anti-CD19 variant and WT IgG1 antibodies tohuman FcγRI (I), R131 FcγRIIa (RIIa), H131 FcγRIIa (HIIa), FcγRIIb(IIb), and V158 FcγRIIIa (VIIIa).

FIGS. 15A-15B. ATP-dependent B cell viability assay demonstrating thesurvival of primary human B cells upon BCR activation, here carried outby crosslinking with anti-mu (FIG. 15A) or anti-CD79b (FIG. 15B)antibodies.

FIG. 16. Inhibition of B cell proliferation by Fc variant anti-CD19antibodies. Anti-RSV (Respiratory Syncytial Virus) S267E/L328F is usedas a control (RSV is not expressed on B cells). An ATP-dependentluminescence assay was used to measure B cell proliferation in thepresence of 10 μg/ml anti-CD79b activating antibody, and the effect ofanti-CD19-S267E/L328F was compared to anti-CD19-IgG1 (native IgG1 Fvcontrol) and anti-RSV-S267E/L328F (non-CD19 Fc control). To assess theimportance of CD19 and FcγRIIb coengagement, anti-RSV-S267E/L328F aloneor in combination with anti-CD19-IgG1 was used.

FIG. 17. Inhibition of B cell proliferation by Fc variant anti-CD19antibodies. An ATP-dependent luminescence assay was used to measureproliferation of primary human B cells in the presence of 1 μg/mlanti-CD79b activating antibody, and varying concentrations of theindicated anti-CD19 or anti-RSV control antibodies.

FIG. 18. Inhibition of B cell proliferation by Fc variant anti-CD19antibodies. An ATP-dependent luminescence assay was used to measureproliferation of primary human B cells in the presence of 2 μg/ml anti-μ(mu) antibody and varying concenrations of the indicated anti-CD19antibodies.

FIG. 19. Coengagement of FcγRIIb and CD19 by IIbE variants inhibits BCRactivation-induced calcium mobilization in primary human B cells.Calcium mobilization was induced with 10 μg/ml anti-CD79b BCR-activatingantibody. Calcium mobilization was measured in the presence of 10 μg/mlfixed concentration of anti-CD19 IIbE variants, α-CD19-IgG1 (native IgG1Fv control), α-FITC-S267E/L328F (non-CD19 Fc control), or PBS vehicle.The data are plotted as the change of MFI over time, or the area underthe response curve normalized to the maximum measured signal intensity.

FIG. 20. Coengagement of FcγRIIb and CD19 by IIbE variants inhibits BCRactivation-induced calcium mobilization in primary human B cells.Calcium mobilization was induced with 10 μg/ml anti-CD79b BCR-activatingantibody. Calcium mobilization was measured at multiple antibodyconcentrations for anti-CD19-IgG1 and three IIbE variants, and the areasunder the curves were plotted to obtain dose-response relationships.

FIG. 21. Correlation between affinity for FcγRIIb and inhibition ofcalcium release. EC50 data are from FIG. 20, and symbols are the same asindicated in FIG. 22. Affinities are from Biacore data presented in FIG.7A-FIG. 7D.

FIG. 22. Coengagement of FcγRIIb and CD19 by IIbE variants inhibits BCRactivation-induced calcium mobilization in primary human B cells.Calcium mobilization was induced with 10 μg/ml anti-CD79b BCR-activatingantibody. Soluble FcγRI (50 □μg/m) added to 10 μg/ml α-CD19-S267E/L328Fcompletely abolished the IIbE variant's inhibitory effect on calciummobilization, confirming the importance of FcγRIIb engagement byanti-CD19 antibody.

FIG. 23. IIbE variant anti-CD19-S267E/L328F activates FcγRIIb-mediatedSHIP phosphorylation in primary human B cells. Anti-CD19-S267E/L328F,anti-CD19-IgG1 (Fv control), anti-RSV-S267E/L328F (Fc control),anti-CD19-Fc KO (Fv control), or anti-FcγRII (10 μg/ml each) were addedto B cells in the presence of 20 μg/ml anti-CD79b antibody. As apositive control, 20 μg/ml goat anti-mouse IgG F(ab′)2 fragment was usedto crosslink anti-CD79b and anti-FcγRII antibodies. A blot of totalcellular extracts was probed with anti-pSHIP, with anti-GAPDH used as aloading control. Relative to negative controls, anti-CD19-S267E/L328Finduced greater SHIP1 phosphorylation than direct crosslinking of BCRand FcγRIIb by CD79b and FcγRIIb antibodies.

FIG. 24. Anti-CD19-S267E/L328F inhibits the anti-apoptotic effects ofBCR activation on primary human B cells. Inhibition of BCR-mediatedsurvival signals by FcγRIIb and CD19 coengagement was examined usingannexin-V staining in the presence of 10 μg/ml anti-CD79b. B cellapoptosis was stimulated by anti-CD19-S267E/L328F, but notanti-CD19-IgG1 (Fv control), anti-RSV-S267E/L328F (Fc control), or thetwo controls combined.

FIG. 25. NK-cell mediated ADCC activity of Fc variant antibodies againstRamos B cells.

FIG. 26. Macrophage mediated phagocytosis (ADCP) activity of Fc variantantibodies against RS4; 11 B cells.

FIG. 27. Fc variant anti-CD19 antibodies do not mediate CDC activityagainst Raji B cells.

FIGS. 28A-28B. Evaluation of the capacity of co-engagement of CD19 andFcγRIIb to inhibit human B cell activation in vivo. (FIG. 28A) Schematicrepresentation of the experimental protocol. (FIG. 28B) Titer ofanti-tetanus toxoid (TT) specific antibody in huPBL-SCID mice after TTimmunization and treatment with vehicle (PBS), anti-CD19 IgG1 WT,anti-CD19 with enhanced FcγRIIb affinity (a-CD19 S267E/L328F), oranti-CD20 (Rituximab).

FIG. 29. Target antigens that may be effective FcγRIIb co-targets formodulation of cellular activity. B=B cells, Plasma=plasma cells,DC=dendritic cells, MΦ=macrophages, PMN=neutrophils, Baso=basophils,Eos=eosinophils, and Mast=mast cells.

FIG. 30. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 1 μg/ml anti-CD79b-SN8-G236R/L328R antibody, andvarying concentrations of either enhanced FcγRIIb variant (S267E/L328F)or FcγR knockout variant (G236R/L328R or ^236R/L328R) versions ofanti-CD20 (clone PRO70769), -CD52 (Campath), and -CD19 (HuAM4G7)antibodies.

FIG. 31. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 2 μg/ml anti-μ antibody, and varying concentrationsof either enhanced FcγRIIb variant (S267E/L328F), FcγR knockout variant(G236R/L328R), or WT IgG1 versions of anti-CD23 antibodies (clone 5E8 orC11).

FIG. 32. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 2 μg/ml anti-μ antibody, and either enhanced FcγRIIbvariant (S267E/L328F), FcγR knockout variant (G236R/L328R), or WT IgG1versions of the anti-CD79b antibody SN8.

FIG. 33. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 2 μg/ml anti-μ antibody, and varying concentrationsof either enhanced FcγRIIb variant (S267E/L328F), FcγR knockout variant(G236R/L328R), or WT IgG1 versions of anti-CD22 antibody.

FIGS. 34A-34B. ATP-dependent luminescence assay measuring B cellproliferation in the presence of BCR stimulation by (FIG. 34A) 1 μg/mlanti-CD79b-SN8-G236R/L328R antibody or (FIG. 34B) 2 μg/ml anti-μantibody, and varying concentrations of either enhanced FcγRIIb variant(S267E/L328F), FcγR knockout variant (G236R/L328R), or WT IgG1 versionsof anti-CD40 antibodies (clones PFCD40, S2C6, G28.5, and 5D12).

FIG. 35. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 1 μg/ml anti-CD79b-SN8-G236R/L328R antibody, andvarying concentrations of either enhanced FcγRIIb variant (S267E/L328F)or FcγR knockout variant (G236R/L328R or ^236R/L328R) versions ofanti-CD19 antibodies (clones HD37, 21 D4, or HuAM4G7.

FIGS. 36A-36D. Calcium release assay measuring inhibition capacity ofvariant antibodies with specificity for CD22 (FIG. 36A), CD23 (FIG.36B), CD40 (FIG. 36C), and CD79b (FIG. 36D). Calcium mobilization wasinduced with 10 μg/ml anti-CD79b-SN8-G236R/L328R antibody, and monitoredin the presence of either enhanced FcγRIIb variant (S267E/L328F) or FcγRknockout variant (G236R/L328R) versions of anti-CD22, -CD23, -CD40, andCD79b antibodies.

FIG. 37. Hapten approach to screening target antigens for capacity tomodulate cellular activity upon high affinity co-targeting with FcγRIIb.

FIG. 38. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 2 μg/ml FITCylated anti-μ F(ab′)2 and varyingconcentrations of either enhanced FcγRIIb variant (S267E/L328F), FcγRknockout variant (G236R/L328R or ^236R/L328R), or WT IgG1 versions ofanti-FITC antibody (clone 4-4-20). Anti-RSV was included as a control.

FIG. 39. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 2 μg/ml anti-μ F(ab′)2, 0.5 μg/ml FITC-labeledanti-CD19 (clone murine 4G7 IgG1), and varying concentrations of eitherenhanced FcγRIIb variant (S267E/L328F), FcγR knockout variant(^236R/L328R), or WT IgG1 versions of anti-FITC antibody.

FIGS. 40A-40B. ATP-dependent luminescence assay measuring B cellproliferation in the presence of 2 μg/ml anti-μ F(ab′)2, 0.5 μg/mlFITC-labeled anti-CD20 clone PDR-79 (FIG. 40A) or 1 μg/ml FITC-labeledRituxan (FIG. 40B), and varying concentrations of either enhancedFcγRIIb variant (S267E/L328F), FcγR knockout variant (^236R/L328R), orWT IgG1 versions of anti-FITC antibody. FITC-labeled anti-mu at 2 μg/mlis also included in (FIG. 40B) as a control.

FIG. 41. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 1 μg/ml anti-CD79b (SN8) antibody, 0.5 μg/mlFITC-labeled anti-CD21, and varying concentrations of either enhancedFcγRIIb variant (S267E/L328F) or WT IgG1 versions of anti-FITC antibody.

FIG. 42. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 1 μg/ml anti-CD79b (SN8) antibody, 0.5 μg/mlFITC-labeled anti-CD24, and varying concentrations of either enhancedFcγRIIb variant (S267E/L328F) or WT IgG1 versions of anti-FITC antibody.

FIG. 43. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 2 μg/ml anti-μ F(ab′)2, 0.25 μg/ml FITC-labeledanti-CD1 or 0.5 μg/ml FITC-labeled anti-CD24, and varying concentrationsof either enhanced FcγRIIb variant (S267E/L328F) or WT IgG1 versions ofanti-FITC antibody.

FIG. 44. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 1 μg/ml anti-CD79b (SN8) antibody, FITC-labeledanti-CD35, and varying concentrations of either enhanced FcγRIIb variant(S267E/L328F) or FcγR knockout (G236R/L328R) versions of anti-FITCantibody.

FIG. 45. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 1 μg/ml anti-CD79b (SN8) antibody, FITC-labeledanti-CD45RA, and varying concentrations of either enhanced FcγRIIbvariant (S267E/L328F) or FcγR knockout (G236R/L328R) versions ofanti-FITC antibody.

FIG. 46. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 1 μg/ml anti-CD79b (SN8) antibody, FITC-labeledanti-CD72, and varying concentrations of either enhanced FcγRIIb variant(S267E/L328F) or FcγR knockout (G236R/L328R) versions of anti-FITCantibody.

FIG. 47. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 2 μg/ml anti-μ F(ab′)2, 2 μg/ml FITC-labeledanti-CD79a (clone ZL7-4), and varying concentrations of either enhancedFcγRIIb variant (S267E/L328F), FcγR knockout (^236R/L328R) or WT IgG1versions of anti-FITC antibody.

FIG. 48. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 2 μg/ml anti-μ F(ab′)2, 1.8 μg/ml FITC-labeledanti-CD79b (clone ZL9-3), and varying concentrations of either enhancedFcγRIIb variant (S267E/L328F), FcγR knockout (^236R/L328R) or WT IgG1versions of anti-FITC antibody.

FIG. 49. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 1 μg/ml anti-CD79b (SN8) antibody, FITC-labeledanti-CD80, and varying concentrations of either enhanced FcγRIIb variant(S267E/L328F) or FcγR knockout (G236R/L328R) versions of anti-FITCantibody.

FIG. 50. ATP-dependent luminescence assay measuring B cell proliferationin the presence of FITC-labeled anti-CD81, varying concentrations ofeither enhanced FcγRIIb variant (S267E/L328F), FcγR knockout variant(G236R/L328R), or WT IgG1 versions of anti-FITC antibody, and 2 μg/mlanti-μ antibody.

FIG. 51. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 1 μg/ml anti-CD79b(SN8)-G236R/L328R antibody,FITC-labeled anti-CD86, and varying concentrations of either enhancedFcγRIIb variant (S267E/L328F) or FcγR knockout (G236R/L328R) versions ofanti-FITC antibody.

FIG. 52. ATP-dependent luminescence assay measuring B cell proliferationin the presence of 1 μg/ml anti-CD79b(SN8)-G236R/L328R antibody,FITC-labeled anti-HLA-DR, and varying concentrations of either enhancedFcγRIIb variant (S267E/L328F) or FcγR knockout (G236R/L328R) versions ofanti-FITC antibody.

FIG. 53. Summary of results from target antigen screening for capacityof antigens to modulate B cell activation when co-targeted with highaffinity FcγRIIb binding. Results are from the ATP-dependenceluminscence B cell viability assay or calcium mobilization assay usingeither Fc variant versions of antibodies with specificity for theindicated target antigens (Fc variant approach) or Fc variant versionsof the anti-FITC antibody together with commercial antibodies withspecificity for the indicated target antigens (Hapten approach)

FIGS. 54A-54D. FIG. 54A lists the amino acid sequences of variousvariable regions, heavy chain constant regions, and full lengthantibodies. FIG. 54B is a continuation of the list in FIG. 54A. FIG. 54Cis a continuation of the list in FIG. 54A and FIG. 54B. FIG. 54D is acontinuation of the list in FIG. 54A, FIG. 54B, and FIG. 54C.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The humoral immune response (e.g., the result of diverse B cellresponses) may be initiated when B cells are activated by an antigen andsubsequently differentiated into plasma cells. Binding of membrane boundB cell receptor (BCR) on B cells by an antigen activates anintracellular signaling cascade, including calcium mobilization, whichleads to cell proliferation and differentiation. Coengagement of cognateBCR) with the inhibitory Fc receptor (FcγRIIb) inhibits B cellactivation signals through a negative feedback loop.

The importance of FcγRIIb in negative regulation of B cell responses hasbeen demonstrated using FcγRIIb-deficient mice, which fail to regulatehumoral responses (Wernersson, S. et al., 1999, J. Immunol. 163,618-622), are sensitized to collagen-induced arthritis (Yuasa, T. etal., 1999, J. Exp. Med. 189, 187-194), and develop lupus-like disease(Fukuyama, H. et al., J. V., 2005, Nat. Immunol. 6, 99-106; McGaha, T.L. et al., 2005, Science 307, 590-593) and Goodpasture's syndrome(Nakamura, A. et al., 2000, J. Exp. Med. 191, 899-906). FcγRIIbdysregulation has also been associated with human autoimmune disease.For example, polymorphisms in the promoter (Blank, M. C. et al., 2005,Hum. Genet. 117, 220-227; Olferiev, M. et al., 2007, J. Biol. Chem. 282,1738-1746) and transmembrane domain (Chen, J. Y. et al., 2006, ArthritisRheum. 54, 3908-3917; Floto, R. A. et al., Nat. Med. 11, 1056-1058; Li,X. et al., 2003, Arthritis Rheum. 48, 3242-3252) of FcγRIIb have beenlinked with increased prevalence of systemic lupus erythematosus (SLE).SLE patients also show reduced FcγRIIb surface expression on B cells(Mackay, M. et al., 2006, J. Exp. Med. 203, 2157-2164; Su, K. et al.,2007, J. Immunol. 178, 3272-3280) and, as a consequence, exhibitdysregulated calcium signaling (Mackay, M. et al., 2006, J. Exp. Med.203, 2157-2164). The pivotal role of FcγRIIb in regulating B cells,supported by mouse models and clinical evidence, makes it an attractivetherapeutic target for controlling autoimmune and inflammatory disorders(Pritchard, N. R. & Smith, K. G., 2003, Immunology 108, 263-273;Ravetch, J. V. & Lanier, L. L., 2000, Science 290, 84-89; Stefanescu, R.N. et al., 2004, J. Clin. Immunol. 24, 315-326).

Described herein are antibodies that mimic the inhibitory effects ofcoengagement of cognate BCR with FcγRIIb on B cells. For example,describe herein are variant anti-CD19 antibodies engineered such thatthe Fc domain binds to FcγRIIb with up to ˜430-fold greater affinity.Relative to native IgG1, the FcγRIIb binding-enhanced (IIbE) variantsstrongly inhibit BCR-induced calcium mobilization and viability inprimary human B cells. Inhibitory effects involved phosphorylation ofSH2-containing inositol polyphosphate 5-phosphatase (SHIP), which isknown to be involved in FcγRIIb-induced negative feedback of B cellactivation. Coengagement of BCR and FcγRIIb by IIbE variants alsoovercame the anti-apoptotic effects of BCR activation. The use of asingle antibody to suppress B cell functions by coengagement of cognateBCR and FcγRIIb may represent a novel approach in the treatment of Bcell-mediated diseases. Nonlimiting examples of B cell-mediated diseasesinclude hematological malignancies, autoimmunity, allergic responses,etc.

Described herein are several definitions. Such definitions are meant toencompass grammatical equivalents.

By “ADCC” or “antibody dependent cell-mediated cytotoxicity” as usedherein is meant the cell-mediated reaction wherein nonspecific cytotoxiccells that express FcγRs recognize bound antibody on a target cell andsubsequently cause lysis of the target cell.

By “ADCP” or antibody dependent cell-mediated phagocytosis as usedherein is meant the cell-mediated reaction wherein nonspecific cytotoxiccells that express FcγRs recognize bound antibody on a target cell andsubsequently cause phagocytosis of the target cell.

By “antibody” herein is meant a protein consisting of one or morepolypeptides substantially encoded by all or part of the recognizedimmunoglobulin genes. The recognized immunoglobulin genes, for examplein humans, include the kappa (κ), lambda (λ), and heavy chain geneticloci, which together comprise the myriad variable region genes, and theconstant region genes mu (υ), delta (δ), gamma (γ), sigma (σ), and alpha(α) which encode the IgM, IgD, IgG (IgG1, IgG2, IgG3, and IgG4), IgE,and IgA (IgA1 and IgA2) isotypes respectively. Antibody herein is meantto include full length antibodies and antibody fragments, and may referto a natural antibody from any organism, an engineered antibody, or anantibody generated recombinantly for experimental, therapeutic, or otherpurposes.

By “amino acid” and “amino acid identity” as used herein is meant one ofthe 20 naturally occurring amino acids or any non-natural analogues thatmay be present at a specific, defined position.

By “CD32b⁺ cell” or “FcγRIIb⁺ cell” as used herein is meant any cell orcell type that expresses CD32b (FcγRIIb). CD32b+ cells include but arenot limited to B cells, plasma cells, dendritic cells, macrophages,neutrophils, mast cells, basophils, or eosinophils.

By “CDC” or “complement dependent cytotoxicity” as used herein is meantthe reaction wherein one or more complement protein components recognizebound antibody on a target cell and subsequently cause lysis of thetarget cell.

By “constant region” of an antibody as defined herein is meant theregion of the antibody that is encoded by one of the light or heavychain immunoglobulin constant region genes. By “constant light chain” or“light chain constant region” as used herein is meant the region of anantibody encoded by the kappa (Cκ) or lambda (Cλ) light chains. Theconstant light chain typically comprises a single domain, and as definedherein refers to positions 108-214 of Cκ or Cλ, wherein numbering isaccording to the EU index. By “constant heavy chain” or “heavy chainconstant region” as used herein is meant the region of an antibodyencoded by the mu, delta, gamma, alpha, or epsilon genes to define theantibody's isotype as IgM, IgD, IgG, IgA, or IgE, respectively. For fulllength IgG antibodies, the constant heavy chain, as defined herein,refers to the N-terminus of the CH1 domain to the C-terminus of the CH3domain, thus comprising positions 118-447, wherein numbering isaccording to the EU index.

By “effector function” as used herein is meant a biochemical event thatresults from the interaction of an antibody Fc region with an Fcreceptor or ligand. Effector functions include FcγR-mediated effectorfunctions such as ADCC and ADCP, and complement-mediated effectorfunctions such as CDC. Further, effector functions includeFcγRIIb-mediated effector functions, such as inhibitory functions (e.g.,downregulating, reducing, inhibiting etc., B cell responses, e.g., ahumoral immune response).

By “effector cell” as used herein is meant a cell of the immune systemthat expresses one or more Fc and/or complement receptors and mediatesone or more effector functions. Effector cells include but are notlimited to monocytes, macrophages, neutrophils, dendritic cells,eosinophils, mast cells, platelets, B cells, large granular lymphocytes,Langerhans' cells, natural killer (NK) cells, and γδ T cells, and may befrom any organism including but not limited to humans, mice, rats,rabbits, and monkeys.

By “Fab” or “Fab region” as used herein is meant the polypeptides thatcomprise the V_(H), CH1, V_(H), and C_(L) immunoglobulin domains. Fabmay refer to this region in isolation, or this region in the context ofa full length antibody or antibody fragment.

By “Fc” or “Fc region”, as used herein is meant the polypeptidecomprising the constant region of an antibody excluding the firstconstant region immunoglobulin domain and in some cases, part of thehinge. Thus Fc refers to the last two constant region immunoglobulindomains of IgA, IgD, and IgG, and the last three constant regionimmunoglobulin domains of IgE and IgM, and the flexible hinge N-terminalto these domains. For IgA and IgM, Fc may include the J chain. For IgG,Fc comprises immunoglobulin domains Cgamma2 and Cgamma3 (Cγ2 and Cγ3)and the hinge between Cgamma1 (Cγ1) and Cgamma2 (Cγ2). Although theboundaries of the Fc region may vary, the human IgG heavy chain Fcregion is usually defined to comprise residues C226 or P230 to itscarboxyl-terminus, wherein the numbering is according to the EU index asin Kabat. Fc may refer to this region in isolation, or this region inthe context of an Fc polypeptide, as described below.

By “Fc polypeptide” as used herein is meant a polypeptide that comprisesall or part of an Fc region. Fc polypeptides include antibodies, Fcfusions, isolated Fcs, and Fc fragments. Immunoglobulins may be Fcpolypeptides.

By “Fc fusion” as used herein is meant a protein wherein one or morepolypeptides is operably linked to Fc. Fc fusion is herein meant to besynonymous with the terms “immunoadhesin”, “Ig fusion”, “Ig chimera”,and “receptor globulin” (sometimes with dashes) as used in the prior art(Chamow et al., 1996, Trends Biotechnol 14:52-60; Ashkenazi et al.,1997, Curr Opin Immunol 9:195-200, both hereby entirely incorporated byreference). An Fc fusion combines the Fc region of an immunoglobulinwith a fusion partner, which in general may be any protein, polypeptideor small molecule. The role of the non-Fc part of an Fc fusion, i.e.,the fusion partner, is to mediate target binding, and thus it isfunctionally analogous to the variable regions of an antibody. Virtuallyany protein or small molecule may be linked to Fc to generate an Fcfusion. Protein fusion partners may include, but are not limited to, thetarget-binding region of a receptor, an adhesion molecule, a ligand, anenzyme, a cytokine, a chemokine, or some other protein or proteindomain. Small molecule fusion partners may include any therapeutic agentthat directs the Fc fusion to a therapeutic target. Such targets may beany molecule, e.g., an extracellular receptor that is implicated indisease.

By “Fc gamma receptor” or “FcγR” as used herein is meant any member ofthe family of proteins that bind the IgG antibody Fc region and aresubstantially encoded by the FcγR genes. In humans this family includesbut is not limited to FcγRI (CD64), including isoforms FcγRIa, FcγRIb,and FcγRIc; FcγRII (CD32), including isoforms FcγRIIa (includingallotypes H131 and R131), FcγRIIb (including FcγRIIb-1 and FcγRIIb-2),and FcγRIIc; and FcγRIII (CD16), including isoforms FcγRIIIa (includingallotypes V158 and F158) and FcγRIIIb (including allotypes FcγRIIIb-NA1and FcγRIIIb-NA2) (Jefferis et al., 2002, Immunol Lett 82:57-65,incorporated entirely by reference), as well as any undiscovered humanFcγRs or FcγR isoforms or allotypes. An FcγR may be from any organism,including but not limited to humans, mice, rats, rabbits, and monkeys.Mouse FcγRs include but are not limited to FcγRI (CD64), FcγRII (CD32),FcγRIII (CD16), and FcγRIII-2 (CD16-2), as well as any undiscoveredmouse FcγRs or FcγR isoforms or allotypes.

By “Fc ligand” or “Fc receptor” as used herein is meant a molecule,e.g., a polypeptide, from any organism that binds to the Fc region of anantibody to form an Fc-ligand complex. Fc ligands include but are notlimited to FcγRs, FcγRs, FcγRs, FcRn, C1q, C3, mannan binding lectin,mannose receptor, staphylococcal protein A, streptococcal protein G, andviral FcγR. Fc ligands also include Fc receptor homologs (FcRH), whichare a family of Fc receptors that are homologous to the FcγRs (Davis etal., 2002, Immunological Reviews 190:123-136). Fc ligands may includeundiscovered molecules that bind Fc.

By “full length antibody” as used herein is meant the structure thatconstitutes the natural biological form of an antibody, includingvariable and constant regions. For example, in most mammals, includinghumans and mice, the full length antibody of the IgG isotype is atetramer and consists of two identical pairs of two immunoglobulinchains, each pair having one light and one heavy chain, each light chaincomprising immunoglobulin domains VL and CL, and each heavy chaincomprising immunoglobulin domains VH, Cγ1, Cγ2, and Cγ3. In somemammals, for example in camels and llamas, IgG antibodies may consist ofonly two heavy chains, each heavy chain comprising a variable domainattached to the Fc region.

By “immunoglobulin” herein is meant a protein comprising one or morepolypeptides substantially encoded by immunoglobulin genes.Immunoglobulins include but are not limited to antibodies (includingbispecific antibodies) and Fc fusions. Immunoglobulins may have a numberof structural forms, including but not limited to full lengthantibodies, antibody fragments, and individual immunoglobulin domains.

By “immunoglobulin (Ig) domain” as used herein is meant a region of animmunoglobulin that exists as a distinct structural entity asascertained by one skilled in the art of protein structure. Ig domainstypically have a characteristic β-sandwich folding topology. The knownIg domains in the IgG isotype of antibodies are VH Cγ1, Cγ2, Cγ3, VL,and CL.

By “IgG” or “IgG immunoglobulin” as used herein is meant a polypeptidebelonging to the class of antibodies that are substantially encoded by arecognized immunoglobulin gamma gene. In humans this class comprises thesubclasses or isotypes IgG1, IgG2, IgG3, and IgG4. By “isotype” as usedherein is meant any of the subclasses of immunoglobulins defined by thechemical and antigenic characteristics of their constant regions. Theknown human immunoglobulin isotypes are IgG1, IgG2, IgG3, IgG4, IgA1,IgA2, IgM, IgD, and IgE.

By “modification” herein is meant an alteration in the physical,chemical, or sequence properties of a protein, polypeptide, antibody, orimmunoglobulin. Modifications described herein include amino acidmodifications and glycoform modifications.

By “amino acid modification” herein is meant an amino acid substitution,insertion, and/or deletion in a polypeptide sequence. By “amino acidsubstitution” or “substitution” herein is meant the replacement of anamino acid at a particular position in a parent polypeptide sequencewith another amino acid. For example, the substitution S267E refers to avariant polypeptide, in this case a constant heavy chain variant, inwhich the serine at position 267 is replaced with glutamic acid. By“amino acid insertion” or “insertion” as used herein is meant theaddition of an amino acid at a particular position in a parentpolypeptide sequence. By “amino acid deletion” or “deletion” as usedherein is meant the removal of an amino acid at a particular position ina parent polypeptide sequence.

By “glycoform modification” or “modified glycoform” or “engineeredglycoform” as used herein is meant a carbohydrate composition that iscovalently attached to a protein, for example an antibody, wherein saidcarbohydrate composition differs chemically from that of a parentprotein. Modified glycoform typically refers to the differentcarbohydrate or oligosaccharide; thus for example an Fc variant maycomprise a modified glycoform. Alternatively, modified glycoform mayrefer to the Fc variant that comprises the different carbohydrate oroligosaccharide.

By “parent polypeptide”, “parent protein”, “parent immunogloblin”,“precursor polypeptide”, “precursor protein”, or “precursorimmunoglobulin” as used herein is meant an unmodified polypeptide,protein, or immunoglobulin that is subsequently modified to generate avariant, e.g., any polypeptide, protein or immunoglobulin which servesas a template and/or basis for at least one amino acid modificationdescribed herein. The parent polypeptide may be a naturally occurringpolypeptide, or a variant or engineered version of a naturally occurringpolypeptide. Parent polypeptide may refer to the polypeptide itself,compositions that comprise the parent polypeptide, or the amino acidsequence that encodes it. Accordingly, by “parent Fc polypeptide” asused herein is meant an Fc polypeptide that is modified to generate avariant Fc polypeptide, and by “parent antibody” as used herein is meantan antibody that is modified to generate a variant antibody (e.g., aparent antibody may include, but is not limited to, a protein comprisingthe constant region of a naturally occurring Ig).

By “position” as used herein is meant a location in the sequence of aprotein. Positions may be numbered sequentially, or according to anestablished format, for example the EU index as in Kabat. For example,position 297 is a position in the human antibody IgG1.

By “polypeptide” or “protein” as used herein is meant at least twocovalently attached amino acids, which includes proteins, polypeptides,oligopeptides and peptides.

By “residue” as used herein is meant a position in a protein and itsassociated amino acid identity. For example, Asparagine 297 (alsoreferred to as Asn297, also referred to as N297) is a residue in thehuman antibody IgG1.

By “target antigen” as used herein is meant the molecule that is boundby the variable region of a given antibody, or the fusion partner of anFc fusion. A target antigen may be a protein, carbohydrate, lipid, orother chemical compound. An antibody or Fc fusion is said to be“specific” for a given target antigen based on having affinity for thetarget antigen.

By “target cell” as used herein is meant a cell that expresses a targetantigen.

By “variable region” as used herein is meant the region of animmunoglobulin that comprises one or more Ig domains substantiallyencoded by any of the Vκ, Vλ, and/or VH genes that make up the kappa,lambda, and heavy chain immunoglobulin genetic loci respectively.

By “variant polypeptide”, “polypeptide variant”, or “variant” as usedherein is meant a polypeptide sequence that differs from that of aparent polypeptide sequence by virtue of at least one amino acidmodification. The parent polypeptide may be a naturally occurring orwild-type (WT) polypeptide, or may be a modified version of a WTpolypeptide. Variant polypeptide may refer to the polypeptide itself, acomposition comprising the polypeptide, or the amino sequence thatencodes it. In some embodiments, variant polypeptides disclosed herein(e.g., variant immunoglobulins) may have at least one amino acidmodification compared to the parent polypeptide, e.g. from about one toabout ten amino acid modifications, from about one to about five aminoacid modifications, etc. compared to the parent. The variant polypeptidesequence herein may possess at least about 80% homology with a parentpolypeptide sequence, e.g., at least about 90% homology, 95% homology,etc. Accordingly, by “Fc variant” or “variant Fc” as used herein ismeant an Fc sequence that differs from that of a parent Fc sequence byvirtue of at least one amino acid modification. An Fc variant may onlyencompass an Fc region, or may exist in the context of an antibody, Fcfusion, isolated Fc, Fc fragment, or other polypeptide that issubstantially encoded by Fc. Fc variant may refer to the Fc polypeptideitself, compositions comprising the Fc variant polypeptide, or the aminoacid sequence that encodes it. By “Fc polypeptide variant” or “variantFc polypeptide” as used herein is meant an Fc polypeptide that differsfrom a parent Fc polypeptide by virtue of at least one amino acidmodification. By “protein variant” or “variant protein” as used hereinis meant a protein that differs from a parent protein by virtue of atleast one amino acid modification. By “antibody variant” or “variantantibody” as used herein is meant an antibody that differs from a parentantibody by virtue of at least one amino acid modification. By “IgGvariant” or “variant IgG” as used herein is meant an antibody thatdiffers from a parent IgG by virtue of at least one amino acidmodification. By “immunoglobulin variant” or “variant immunoglobulin” asused herein is meant an immunoglobulin sequence that differs from thatof a parent immunoglobulin sequence by virtue of at least one amino acidmodification.

By “wild type” or “WT” herein is meant an amino acid sequence or anucleotide sequence that is found in nature, including allelicvariations. A WT protein, polypeptide, antibody, immunoglobulin, IgG,etc. has an amino acid sequence or a nucleotide sequence that has notbeen intentionally modified.

Immunoglobulins

As described herein, an immunoglobulin may be an antibody, an Fc fusion,an isolated Fc, an Fc fragment, or an Fc polypeptide. In one embodiment,an immunoglobulin is an antibody.

Antibodies are immunological proteins that bind a specific antigen. Inmost mammals, including humans and mice, antibodies are constructed frompaired heavy and light polypeptide chains. The light and heavy chainvariable regions show significant sequence diversity between antibodies,and are responsible for binding the target antigen. Each chain is madeup of individual immunoglobulin (Ig) domains, and thus the generic termimmunoglobulin is used for such proteins.

Traditional antibody structural units typically comprise a tetramer.Each tetramer is typically composed of two identical pairs ofpolypeptide chains, each pair having one “light” (typically having amolecular weight of about 25 kDa) and one “heavy” chain (typicallyhaving a molecular weight of about 50-70 kDa). Human light chains areclassified as kappa and lambda light chains. Heavy chains are classifiedas mu, delta, gamma, alpha, or epsilon, and define the antibody'sisotype as IgM, IgD, IgG, IgA, and IgE, respectively. IgG has severalsubclasses, including, but not limited to IgG1, IgG2, IgG3, and IgG4.IgM has subclasses, including, but not limited to, IgM1 and IgM2. IgAhas several subclasses, including but not limited to IgA1 and IgA2.Thus, “isotype” as used herein is meant any of the classes andsubclasses of immunoglobulins defined by the chemical and antigeniccharacteristics of their constant regions. The known humanimmunoglobulin isotypes are IgG1, IgG2, IgG3, IgG4, IgA1, IgA2, IgM1,IgM2, IgD, and IgE.

Each of the light and heavy chains are made up of two distinct regions,referred to as the variable and constant regions. The IgG heavy chain iscomposed of four immunoglobulin domains linked from N- to C-terminus inthe order VH-CH1-CH2-CH3, referring to the heavy chain variable domain,heavy chain constant domain 1, heavy chain constant domain 2, and heavychain constant domain 3 respectively (also referred to asVH-Cγ1-Cγ2-Cγ3, referring to the heavy chain variable domain, constantgamma 1 domain, constant gamma 2 domain, and constant gamma 3 domainrespectively). The IgG light chain is composed of two immunoglobulindomains linked from N- to C-terminus in the order VL-CL, referring tothe light chain variable domain and the light chain constant domainrespectively. The constant regions show less sequence diversity, and areresponsible for binding a number of natural proteins to elicit importantbiochemical events. The distinguishing features between these antibodyclasses are their constant regions, although subtler differences mayexist in the variable region.

The variable region of an antibody contains the antigen bindingdeterminants of the molecule, and thus determines the specificity of anantibody for its target antigen. The variable region is so named becauseit is the most distinct in sequence from other antibodies within thesame class. The amino-terminal portion of each chain includes a variableregion of about 100 to 110 or more amino acids primarily responsible forantigen recognition. In the variable region, three loops are gatheredfor each of the V domains of the heavy chain and light chain to form anantigen-binding site. Each of the loops is referred to as acomplementarity-determining region (hereinafter referred to as a “CDR”),in which the variation in the amino acid sequence is most significant.There are 6 CDRs total, three each per heavy and light chain, designatedVH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3. The variableregion outside of the CDRs is referred to as the framework (FR) region.Although not as diverse as the CDRs, sequence variability does occur inthe FR region between different antibodies. Overall, this characteristicarchitecture of antibodies provides a stable scaffold (the FR region)upon which substantial antigen binding diversity (the CDRs) can beexplored by the immune system to obtain specificity for a broad array ofantigens. A number of high-resolution structures are available for avariety of variable region fragments from different organisms, someunbound and some in complex with antigen. Sequence and structuralfeatures of antibody variable regions are disclosed, for example, inMorea et al., 1997, Biophys Chem 68:9-16; Morea et al., 2000, Methods20:267-279, hereby entirely incorporated by reference, and the conservedfeatures of antibodies are disclosed, for example, in Maynard et al.,2000, Annu Rev Biomed Eng 2:339-376, hereby entirely incorporated byreference.

The carboxy-terminal portion of each chain defines a constant regionprimarily responsible for effector function. In the IgG subclass ofimmunoglobulins, there are several immunoglobulin domains in the heavychain. By “immunoglobulin (Ig) domain” herein is meant a region of animmunoglobulin having a distinct tertiary structure. Of interest inembodiments described herein are the heavy chain domains, including, theconstant heavy (CH) domains and the hinge region. In the context of IgGantibodies, the IgG isotypes each have three CH regions. Accordingly,“CH” domains in the context of IgG are as follows: “CH1” refers topositions 118-220 according to the EU index as in Kabat. “CH2” refers topositions 237-340 according to the EU index as in Kabat, and “CH3”refers to positions 341-447 according to the EU index as in Kabat.

Another important region of the heavy chain is the hinge region. By“hinge” or “hinge region” or “antibody hinge region” or “immunoglobulinhinge region” herein is meant the flexible polypeptide comprising theamino acids between the first and second constant domains of anantibody. Structurally, the IgG CH1 domain ends at EU position 220, andthe IgG CH2 domain begins at residue EU position 237. Thus for IgG theantibody hinge is herein defined to include positions 221 (D221 in IgG1)to 236 (G236 in IgG1), wherein the numbering is according to the EUindex as in Kabat. In some embodiments, for example in the context of anFc region, the lower hinge is included, with the “lower hinge” generallyreferring to positions 226 or 230 to 236.

Of interest in embodiments described herein are the Fc regions. By “Fc”or “Fc region”, as used herein is meant the polypeptide comprising theconstant region of an antibody excluding the first constant regionimmunoglobulin domain and in some cases, part of the hinge. Thus Fcrefers to the last two constant region immunoglobulin domains of IgA,IgD, and IgG, and the last three constant region immunoglobulin domainsof IgE and IgM, and the flexible hinge N-terminal to these domains. ForIgA and IgM, Fc may include the J chain. For IgG, Fc comprisesimmunoglobulin domains Cgamma2 and Cgamma3 (Cγ2 and Cγ3) and the lowerhinge region between Cgamma1 (Cγ1) and Cgamma2 (Cγ2). Although theboundaries of the Fc region may vary, the human IgG heavy chain Fcregion is usually defined to include residues C226 or P230 to itscarboxyl-terminus, wherein the numbering is according to the EU index asin Kabat. Fc may refer to this region in isolation, or this region inthe context of an Fc polypeptide, as described below. By “Fcpolypeptide” as used herein is meant a polypeptide that comprises all orpart of an Fc region. Fc polypeptides include antibodies, Fc fusions,isolated Fcs, and Fc fragments.

The Fc region of an antibody interacts with a number of Fc receptors andligands, imparting an array of important functional capabilitiesreferred to as effector functions. For IgG the Fc region, Fc comprisesIg domains Cγ2 and Cγ3 and the N-terminal hinge leading into Cγ2. Animportant family of Fc receptors for the IgG class are the Fc gammareceptors (FcγRs). These receptors mediate communication betweenantibodies and the cellular arm of the immune system (Raghavan et al.,1996, Annu Rev Cell Dev Biol 12:181-220; Ravetch et al., 2001, Annu RevImmunol 19:275-290, both hereby entirely incorporated by reference). Inhumans this protein family includes FcγRI (CD64), including isoformsFcγRIa, FcγRIb, and FcγRIc; FcγRII (CD32), including isoforms FcγRIIa(including allotypes H131 and R131), FcγRIIb (including FcγRIIb-1 andFcγRIIb-2), and FcγRIIc; and FcγRIII (CD16), including isoforms FcγRIIIa(including allotypes V158 and F158) and FcγRIIIb (including allotypesFcγRIIIb-NA1 and FcγRIIIb-NA2) (Jefferis et al., 2002, Immunol Lett82:57-65, hereby entirely incorporated by reference). These receptorstypically have an extracellular domain that mediates binding to Fc, amembrane spanning region, and an intracellular domain that may mediatesome signaling event within the cell. These receptors are expressed in avariety of immune cells including monocytes, macrophages, neutrophils,dendritic cells, eosinophils, mast cells, platelets, B cells, largegranular lymphocytes, Langerhans' cells, natural killer (NK) cells, andγγ T cells. Formation of the Fc/FcγR complex recruits these effectorcells to sites of bound antigen, typically resulting in signaling eventswithin the cells and important subsequent immune responses such asrelease of inflammation mediators, B cell activation, endocytosis,phagocytosis, and cytotoxic attack. The ability to mediate cytotoxic andphagocytic effector functions is a potential mechanism by whichantibodies destroy targeted cells. The cell-mediated reaction whereinnonspecific cytotoxic cells that express FcγRs recognize bound antibodyon a target cell and subsequently cause lysis of the target cell isreferred to as antibody dependent cell-mediated cytotoxicity (ADCC)(Raghavan et al., 1996, Annu Rev Cell Dev Biol 12:181-220; Ghetie etal., 2000, Annu Rev Immunol 18:739-766; Ravetch et al., 2001, Annu RevImmunol 19:275-290, both hereby entirely incorporated by reference). Thecell-mediated reaction wherein nonspecific cytotoxic cells that expressFcγRs recognize bound antibody on a target cell and subsequently causephagocytosis of the target cell is referred to as antibody dependentcell-mediated phagocytosis (ADCP).

The different IgG subclasses have different affinities for the FcγRs,with IgG1 and IgG3 typically binding substantially better to thereceptors than IgG2 and IgG4 (Jefferis et al., 2002, Immunol Lett82:57-65, hereby entirely incorporated by reference). The FcγRs bind theIgG Fc region with different affinities. The extracellular domains ofFcγRIIIa and FcγRIIIb are 96% identical, however FcγRIIIb does not havea intracellular signaling domain. Furthermore, whereas FcγRI, FcγRIIa/c,and FcγRIIIa are positive regulators of immune complex-triggeredactivation, characterized by having an intracellular domain that has animmunoreceptor tyrosine-based activation motif (ITAM), FcγRIIb has animmunoreceptor tyrosine-based inhibition motif (ITIM) and is thereforeinhibitory. Thus the former are referred to as activation receptors, andFcγRIIb is referred to as an inhibitory receptor. Despite thesedifferences in affinities and activities, all FcγRs bind the same regionon Fc, at the N-terminal end of the Cγ2 domain and the preceding hinge.This interaction is well characterized structurally (Sondermann et al.,2001, J Mol Biol 309:737-749, hereby entirely incorporated byreference), and several structures of the human Fc bound to theextracellular domain of human FcγRIIIb have been solved (pdb accessioncode 1E4K) (Sondermann et al., 2000, Nature 406:267-273, hereby entirelyincorporated by reference) (pdb accession codes 1IIS and 1IIX) (Radaevet al., 2001, J Biol Chem 276:16469-16477, hereby entirely incorporatedby reference).

An overlapping but separate site on Fc serves as the interface for thecomplement protein C1q. In the same way that Fc/FcγR binding mediatesADCC, Fc/C1q binding mediates complement dependent cytotoxicity (CDC). Asite on Fc between the Cγ2 and Cγ3 domains mediates interaction with theneonatal receptor FcRn, the binding of which recycles endocytosedantibody from the endosome back to the bloodstream (Raghavan et al.,1996, Annu Rev Cell Dev Biol 12:181-220; Ghetie et al., 2000, Annu RevImmunol 18:739-766, both hereby entirely incorporated by reference).This process, coupled with preclusion of kidney filtration due to thelarge size of the full length molecule, results in favorable antibodyserum half-lives ranging from one to three weeks. Binding of Fc to FcRnalso plays a key role in antibody transport. The binding site for FcRnon Fc is also the site at which the bacterial proteins A and G bind. Thetight binding by these proteins is typically exploited as a means topurify antibodies by employing protein A or protein G affinitychromatography during protein purification. The fidelity of theseregions, the complement and FcRn/protein A binding regions are importantfor both the clinical properties of antibodies and their development.

A key feature of the Fc region is the conserved N-linked glycosylationthat occurs at N297. This carbohydrate, or oligosaccharide as it issometimes referred, plays a critical structural and functional role forthe antibody, and is one of the principle reasons that antibodies mustbe produced using mammalian expression systems. Efficient Fc binding toFcγR and C1q requires this modification, and alterations in thecomposition of the N297 carbohydrate or its elimination affect bindingto these proteins (Umana et al., 1999, Nat Biotechnol 17:176-180; Davieset al., 2001, Biotechnol Bioeng 74:288-294; Mimura et al., 2001, J BiolChem 276:45539-45547.; Radaev et al., 2001, J Biol Chem 276:16478-16483;Shields et al., 2001, J Biol Chem 276:6591-6604; Shields et al., 2002, JBiol Chem 277:26733-26740; Simmons et al., 2002, J Immunol Methods263:133-147, all hereby entirely incorporated by reference).

Immunoglobulins of embodiments described herein may also be anantibody-like protein referred to as an Fc fusion (Chamow et al., 1996,Trends Biotechnol 14:52-60; Ashkenazi et al., 1997, Curr Opin Immunol9:195-200, both incorporated entirely by reference). “Fc fusion” isherein meant to be synonymous with the terms “immunoadhesin”, “Igfusion”, “Ig chimera”, and “receptor globulin” (sometimes with dashes)as used in the prior art (Chamow et al., 1996, Trends Biotechnol14:52-60; Ashkenazi et al., 1997, Curr Opin Immunol 9:195-200). An Fcfusion is a protein wherein one or more polypeptides, herein referred toas a “fusion partner”, is operably linked to Fc. An Fc fusion combinesthe Fc region of an antibody, and thus its favorable effector functionsand pharmacokinetics, with the target-binding region of a receptor,ligand, or some other protein or protein domain. The role of the latteris to mediate target recognition, and thus it is functionally analogousto the antibody variable region. Because of the structural andfunctional overlap of Fc fusions with antibodies, the discussion onantibodies in the present disclosure extends also to Fc fusions.

Virtually any protein or small molecule may be linked to Fc to generatean Fc fusion. Protein fusion partners may include, but are not limitedto, the variable region of any antibody, the target-binding region of areceptor, an adhesion molecule, a ligand, an enzyme, a cytokine, achemokine, or some other protein or protein domain. Small moleculefusion partners may include any agent that directs the Fc fusion to atarget antigen. Such target antigen may be any molecule, e.g., anextracellular receptor, that is implicated in disease. Fc fusions ofembodiments described herein may target virtually antigen that isexpressed on CD32b⁺ cells.

Fusion partners may be linked to any region of an Fc region, includingat the N- or C-termini, or at some residue in-between the termini. Inone embodiment, a fusion partner is linked at the N- or C-terminus ofthe Fc region. A variety of linkers may find use in some embodimentsdescribed herein to covalently link Fc regions to a fusion partner. By“linker”, “linker sequence”, “spacer”, “tethering sequence” orgrammatical equivalents thereof, herein is meant a molecule or group ofmolecules (such as a monomer or polymer) that connects two molecules andoften serves to place the two molecules in a configuration. Linkers areknown in the art; for example, homo- or hetero-bifunctional linkers asare well known (see, 1994 Pierce Chemical Company catalog, technicalsection on cross-linkers, pages 155-200, incorporated entirely byreference). A number of strategies may be used to covalently linkmolecules together. These include, but are not limited to polypeptidelinkages between N- and C-termini of proteins or protein domains,linkage via disulfide bonds, and linkage via chemical cross-linkingreagents. In one aspect of this embodiment, the linker is a peptidebond, generated by recombinant techniques or peptide synthesis. Thelinker peptide may predominantly include the following amino acidresidues: Gly, Ser, Ala, or Thr. The linker peptide should have a lengththat is adequate to link two molecules in such a way that they assumethe correct conformation relative to one another so that they retain thedesired activity. Suitable lengths for this purpose include at least oneand not more than 50 amino acid residues. In one embodiment, the linkeris from about 1 to 30 amino acids in length. In one embodiment, hlinkers of 1 to 20 amino acids in length may be used. Useful linkersinclude glycine-serine polymers (including, for example, (GS)n, (GSGGS)n(set forth as SEQ ID NO:1), (GGGGS)n (set forth as SEQ ID NO:2), and(GGGS)n (set forth as SEQ ID NO:3), where n is an integer of at leastone), glycine-alanine polymers, alanine-serine polymers, and otherflexible linkers, as will be appreciated by those in the art.Alternatively, a variety of nonproteinaceous polymers, including but notlimited to polyethylene glycol (PEG), polypropylene glycol,polyoxyalkylenes, or copolymers of polyethylene glycol and polypropyleneglycol, may find use as linkers, that is may find use to link an Fcregions to a fusion partner.

Also contemplated as fusion partners are Fc polypeptides. Thus animmunoglobulin as described herein may be a multimeric Fc polypeptide,comprising two or more Fc regions. The advantage of such a molecule isthat it provides multiple binding sites for Fc receptors with a singleprotein molecule. In one embodiment, Fc regions may be linked using achemical engineering approach. For example, Fab's and Fc's may be linkedby thioether bonds originating at cysteine residues in the hinges,generating molecules such as FabFc₂. Fc regions may be linked usingdisulfide engineering and/or chemical cross-linking. In one embodiment,Fc regions may be linked genetically. In one embodiment, Fc regions inan immunoglobulin are linked genetically to generated tandemly linked Fcregions as described in U.S. Ser. No. 11/022,289, filed Dec. 21, 2004,entitled “Fc polypeptides with novel Fc ligand binding sites,”incorporated entirely by reference. Tandemly linked Fc polypeptides maycomprise two or more Fc regions, e.g., one to three Fc regions, two Fcregions. It may be advantageous to explore a number of engineeringconstructs in order to obtain homo- or hetero-tandemly linked Fc regionswith the most favorable structural and functional properties. Tandemlylinked Fc regions may be homo-tandemly linked Fc regions, that is an Fcregion of one isotype is fused genetically to another Fc region of thesame isotype. It is anticipated that because there are multiple FcγR,C1q, and/or FcRn binding sites on tandemly linked Fc polypeptides,effector functions and/or pharmacokinetics may be enhanced. In analternate embodiment, Fc regions from different isotypes may be tandemlylinked, referred to as hetero-tandemly linked Fc regions. For example,because of the capacity to target FcγR and FcαRI receptors, animmunoglobulin that binds both FcγRs and FcαRI may provide a significantclinical improvement.

The immunoglobulins of embodiments disclosed herein may be substantiallyencoded by immunoglobulin genes belonging to any of the antibodyclasses. In certain embodiments, the immunoglobulins disclosed hereinfind use in antibodies or Fc fusions that comprise sequences belongingto the IgG class of antibodies, including IgG1, IgG2, IgG3, or IgG4.FIG. 1 provides an alignment of these human IgG sequences. In alternateembodiments, immunoglobulins disclosed herein find use in antibodies orFc fusions that comprise sequences belonging to the IgA (includingsubclasses IgA1 and IgA2), IgD, IgE, IgG, or IgM classes of antibodies.The immunoglobulins disclosed herein may comprise more than one proteinchain, e.g., may be an antibody or Fc fusion that is a monomer or anoligomer, including a homo- or hetero-oligomer.

Immunoglobulins disclosed herein may be substantially encoded by genesfrom any organism, e.g., mammals (including, but not limited to humans,rodents (including but not limited to mice and rats), lagomorpha(including but not limited to rabbits and hares), camelidae (includingbut not limited to camels, llamas, and dromedaries), and non-humanprimates, including but not limited to Prosimians, Platyrrhini (NewWorld monkeys), Cercopithecoidea (Old World monkeys), and Hominoideaincluding the Gibbons and Lesser and Great Apes. In a certainembodiments, the immunoglobulins disclosed herein may be substantiallyhuman.

As is well known in the art, immunoglobulin polymorphisms exist in thehuman population. Gm polymorphism is determined by the IGHG1, IGHG2 andIGHG3 genes which have alleles encoding allotypic antigenic determinantsreferred to as G1m, G2m, and G3m allotypes for markers of the humanIgG1, IgG2 and IgG3 molecules (no Gm allotypes have been found on thegamma 4 chain). Markers may be classified into ‘allotypes’ and‘isoallotypes’. These are distinguished on different serological basesdependent upon the strong sequence homologies between isotypes.Allotypes are antigenic determinants specified by allelic forms of theIg genes. Allotypes represent slight differences in the amino acidsequences of heavy or light chains of different individuals. Even asingle amino acid difference can give rise to an allotypic determinant,although in many cases there are several amino acid substitutions thathave occurred. Allotypes are sequence differences between alleles of asubclass whereby the antisera recognize only the allelic differences. Anisoallotype is an allele in one isotype which produces an epitope whichis shared with a non-polymorphic homologous region of one or more otherisotypes and because of this the antisera will react with both therelevant allotypes and the relevant homologous isotypes (Clark, 1997,IgG effector mechanisms, Chem Immunol. 65:88-110; Gorman & Clark, 1990,Semin Immunol 2(6):457-66, both hereby entirely incorporated byreference).

Allelic forms of human immunoglobulins have been well-characterized (WHOReview of the notation for the allotypic and related markers of humanimmunoglobulins. J Immunogen 1976, 3: 357-362; WHO Review of thenotation for the allotypic and related markers of human immunoglobulins.1976, Eur. J. Immunol. 6, 599-601; Loghem E van, 1986, Allotypicmarkers, Monogr Allergy 19: 40-51, all hereby entirely incorporated byreference). Additionally, other polymorphisms have been characterized(Kim et al., 2001, J. Mol. Evol. 54:1-9, hereby entirely incorporated byreference). At present, 18 Gm allotypes are known: G1m (1, 2, 3, 17) orG1m (a, x, f, z), G2m (23) or G2m (n), G3m (5, 6, 10, 11, 13, 14, 15,16, 21, 24, 26, 27, 28) or G3m (b1, c3, b5, b0, b3, b4, s, t, g1, c5, u,v, g5) (Lefranc, et al., The human IgG subclasses: molecular analysis ofstructure, function and regulation. Pergamon, Oxford, pp. 43-78 (1990);Lefranc, G. et al., 1979, Hum. Genet.: 50, 199-211, both hereby entirelyincorporated by reference). Allotypes that are inherited in fixedcombinations are called Gm haplotypes. FIG. 2 shows common haplotypes ofthe gamma chain of human IgG1 (FIG. 2A) and IgG2 (FIG. 2A) showing thepositions and the relevant amino acid substitutions. The immunoglobulinsdisclosed herein may be substantially encoded by any allotype,isoallotype, or haplotype of any immunoglobulin gene.

The immunoglobulins disclosed herein may compose an Fc polypeptide,including but not limited to antibodies, isolated Fcs, Fc fragments, andFc fusions. In one embodiment, an immunoglobulin disclosed herein is afull length antibody, constituting the natural biological form of anantibody, including variable and constant regions. For the IgG isotypefull length antibody is a tetramer and consists of two identical pairsof two immunoglobulin chains, each pair having one light and one heavychain, each light chain comprising immunoglobulin domains VL and CL, andeach heavy chain comprising immunoglobulin domains VH, Cγ1, Cγ2, andCγ3. In another embodiment, immunoglobulins disclosed herein areisolated Fc regions or Fc fragments.

Immunoglobulins disclosed herein may be a variety of structures,including, but not limited antibody fragments, bispecific antibodies,minibodies, domain antibodies, synthetic antibodies (sometimes referredto herein as “antibody mimetics”), chimeric antibodies, humanizedantibodies, antibody fusions (sometimes referred to as “antibodyconjugates”), and fragments of each, respectively.

In one embodiment, the antibody is an antibody fragment. Specificantibody fragments include, but are not limited to, (i) the Fab fragmentconsisting of VL, VH, CL and CH1 domains, (ii) the Fd fragmentconsisting of the VH and CH1 domains, (iii) the Fv fragment consistingof the VL and VH domains of a single antibody; (iv) the dAb fragment,which consists of a single variable, (v) isolated CDR regions, (vi)F(ab′)2 fragments, a bivalent fragment comprising two linked Fabfragments (vii) single chain Fv molecules (scFv), wherein a VH domainand a VL domain are linked by a peptide linker which allows the twodomains to associate to form an antigen binding site, (viii) bispecificsingle chain Fv dimers, and (ix) “diabodies” or “triabodies”,multivalent or multispecific fragments constructed by gene fusion. Theantibody fragments may be modified. For example, the molecules may bestabilized by the incorporation of disulphide bridges linking the VH andVL domains. Examples of antibody formats and architectures are describedin Holliger & Hudson, 2006, Nature Biotechnology 23(9):1126-1136, andCarter 2006, Nature Reviews Immunology 6:343-357 and references citedtherein, all expressly incorporated by reference.

In one embodiment, an antibody disclosed herein may be a multispecificantibody, and notably a bispecific antibody, also sometimes referred toas “diabodies”. These are antibodies that bind to two (or more)different antigens. Diabodies can be manufactured in a variety of waysknown in the art, e.g., prepared chemically or from hybrid hybridomas.In one embodiment, the antibody is a minibody. Minibodies are minimizedantibody-like proteins comprising a scFv joined to a CH3 domain. In somecases, the scFv can be joined to the Fc region, and may include some orall of the hinge region. For a description of multispecific antibodiessee Holliger & Hudson, 2006, Nature Biotechnology 23(9):1126-1136 andreferences cited therein, all expressly incorporated by reference.

Nonhuman, Chimeric, Humanized, and Fully Human Antibodies

The variable region of an antibody, as is well known in the art, cancompose sequences from a variety of species. In some embodiments, theantibody variable region can be from a nonhuman source, including butnot limited to mice, rats, rabbits, camels, llamas, and monkeys. In someembodiments, the scaffold components can be a mixture from differentspecies. As such, an antibody disclosed herein may be a chimericantibody and/or a humanized antibody. In general, both “chimericantibodies” and “humanized antibodies” refer to antibodies that combineregions from more than one species. For example, “chimeric antibodies”traditionally comprise variable region(s) from a mouse or other nonhumanspecies and the constant region(s) from a human.

“Humanized antibodies” generally refer to non-human antibodies that havehad the variable-domain framework regions swapped for sequences found inhuman antibodies. Generally, in a humanized antibody, the entireantibody, except the CDRs, is encoded by a polynucleotide of humanorigin or is identical to such an antibody except within its CDRs. TheCDRs, some or all of which are encoded by nucleic acids originating in anon-human organism, are grafted into the beta-sheet framework of a humanantibody variable region to create an antibody, the specificity of whichis determined by the engrafted CDRs. The creation of such antibodies isdescribed in, e.g., WO 92/11018, Jones, 1986, Nature 321:522-525,Verhoeyen et al., 1988, Science 239:1534-1536. “Backmutation” ofselected acceptor framework residues to the corresponding donor residuesis often required to regain affinity that is lost in the initial graftedconstruct (U.S. Pat. No. 5,693,762, incorporated entirely by reference.The humanized antibody optimally also will comprise at least a portionof an immunoglobulin constant region, typically that of a humanimmunoglobulin, and thus will typically comprise a human Fc region.Humanized antibodies can also be generated using mice with a geneticallyengineered immune system. Roque et al., 2004, Biotechnol. Prog.20:639-654. A variety of techniques and methods for humanizing andreshaping non-human antibodies are well known in the art (See Tsurushita& Vasquez, 2004, Humanization of Monoclonal Antibodies, MolecularBiology of B Cells, 533-545, Elsevier Science (USA), and referencescited therein). Humanization or other methods of reducing theimmunogenicity of nonhuman antibody variable regions may includeresurfacing methods, as described for example in Roguska et al., 1994,Proc. Natl. Acad. Sci. USA 91:969-973. In one embodiment, the parentantibody has been affinity matured, as is known in the art.Structure-based methods may be employed for humanization and affinitymaturation, for example as described in U.S. Ser. No. 11/004,590.Selection based methods may be employed to humanize and/or affinitymature antibody variable regions, that is, to increase the affinity ofthe variable region for its target antigen. Other humanization methodsmay involve the grafting of only parts of the CDRs, including but notlimited to methods described in U.S. Ser. No. 09/810,502; Tan et al.,2002, J. Immunol. 169:1119-1125; De Pascalis et al., 2002, J. Immunol.169:3076-3084. Structure-based methods may be employed for humanizationand affinity maturation, for example as described in U.S. Ser. No.10/153,159 and related applications, all incorporated entirely byreference. In certain variations, the immunogenicity of the antibody isreduced using a method described in U.S. Ser. No. 11/004,590, entitled“Methods of Generating Variant Proteins with Increased Host StringContent and Compositions Thereof”, filed on Dec. 3, 2004, incorporatedentirely by reference.

In one embodiment, the antibody is a fully human antibody with at leastone modification as outlined herein. “Fully human antibody” or “completehuman antibody” refers to a human antibody having the gene sequence ofan antibody derived from a human chromosome with the modificationsoutlined herein. Fully human antibodies may be obtained, for example,using transgenic mice (Bruggemann et al., 1997, Curr Opin Biotechnol8:455-458) or human antibody libraries coupled with selection methods(Griffiths et al., 1998, Curr Opin Biotechnol 9:102-108).

Target Antigens

Virtually any antigen may be targeted by the immunoglobulins disclosedherein, including but not limited to proteins, subunits, domains,motifs, and/or epitopes belonging to the following list of targets:17-IA, 4-1BB, 4Dc, 6-keto-PGF1a, 8-iso-PGF2a, 8-oxo-dG, A1 AdenosineReceptor, A33, ACE, ACE-2, Activin, Activin A, Activin AB, Activin B,Activin C, Activin RIA, Activin RIA ALK-2, Activin RIB ALK-4, ActivinRIIA, Activin RIIB, ADAM, ADAM10, ADAM12, ADAM15, ADAM17/TACE, ADAMS,ADAM9, ADAMTS, ADAMTS4, ADAMTS5, Addressins, aFGF, ALCAM, ALK, ALK-1,ALK-7, alpha-1-antitrypsin, alpha-V/beta-1 antagonist, ANG, Ang, APAF-1,APE, APJ, APP, APRIL, AR, ARC, ART, Artemin, anti-Id, ASPARTIC, Atrialnatriuretic factor, av/b3 integrin, Axl, b2M, B7-1, B7-2, B7-H,B-lymphocyte Stimulator (BlyS), BACE, BACE-1, Bad, BAFF, BAFF-R, Bag-1,BAK, Bax, BCA-1, BCAM, Bcl, BCMA, BDNF, b-ECGF, bFGF, BID, Bik, BIM,BLC, BL-CAM, BLK, BMP, BMP-2 BMP-2a, BMP-3 Osteogenin, BMP-4 BMP-2b,BMP-5, BMP-6 Vgr-1, BMP-7 (OP-1), BMP-8 (BMP-8a, OP-2), BMPR, BMPR-IA(ALK-3), BMPR-IB (ALK-6), BRK-2, RPK-1, BMPR-II (BRK-3), BMPs, b-NGF,BOK, Bombesin, Bone-derived neurotrophic factor, BPDE, BPDE-DNA, BTC,complement factor 3 (C3), C3a, C4, C5, C5a, C10, CA125, CAD-8,Calcitonin, cAMP, carcinoembryonic antigen (CEA), carcinoma-associatedantigen, Cathepsin A, Cathepsin B, Cathepsin C/DPPI, Cathepsin D,Cathepsin E, Cathepsin H, Cathepsin L, Cathepsin 0, Cathepsin S,Cathepsin V, Cathepsin X/Z/P, CBL, CCI, CCK2, CCL, CCL1, CCL11, CCL12,CCL13, CCL14, CCL15, CCL16, CCL17, CCL18, CCL19, CCL2, CCL20, CCL21,CCL22, CCL23, CCL24, CCL25, CCL26, CCL27, CCL28, CCL3, CCL4, CCL5, CCL6,CCL7, CCL8, CCL9/10, CCR, CCR1, CCR10, CCR10, CCR2, CCR3, CCR4, CCR5,CCR6, CCR7, CCR8, CCR9, CD1, CD2, CD3, CD3E, CD4, CD5, CD6, CD7, CD8,CD10, CD11a, CD11b, CD11c, CD13, CD14, CD15, CD16, CD18, CD19, CD20,CD21, CD22, CD23, CD25, CD27L, CD28, CD29, CD30, CD30L, CD32, CD33 (p67proteins), CD34, CD38, CD40, CD40L, CD44, CD45, CD46, CD49a, CD52, CD54,CD55, CD56, CD61, CD64, CD66e, CD74, CD80 (B7-1), CD89, CD95, CD123,CD137, CD138, CD140a, CD146, CD147, CD148, CD152, CD164, CEACAM5, CFTR,cGMP, CINC, Clostridium botulinum toxin, Clostridium perfringens toxin,CKb8-1, CLC, CMV, CMV UL, CNTF, CNTN-1, COX, C-Ret, CRG-2, CT-1, CTACK,CTGF, CTLA-4, CX3CL1, CX3CR1, CXCL, CXCL1, CXCL2, CXCL3, CXCL4, CXCL5,CXCL6, CXCL7, CXCL8, CXCL9, CXCL10, CXCL11, CXCL12, CXCL13, CXCL14,CXCL15, CXCL16, CXCR, CXCR1, CXCR2, CXCR3, CXCR4, CXCR5, CXCR6,cytokeratin tumor-associated antigen, DAN, DCC, DcR3, DC-SIGN, Decayaccelerating factor, des(1-3)-IGF-1 (brain IGF-1), Dhh, digoxin, DNAM-1,Dnase, Dpp, DPPIV/CD26, Dtk, ECAD, EDA, EDA-A1, EDA-A2, EDAR, EGF, EGFR(ErbB-1), EMA, EMMPRIN, ENA, endothelin receptor, Enkephalinase, eNOS,Eot, eotaxin1, EpCAM, Ephrin B2/EphB4, EPO, ERCC, E-selectin, ET-1,Factor IIa, Factor VII, Factor VIIIc, Factor IX, fibroblast activationprotein (FAP), Fas, FcR1, FEN-1, Ferritin, FGF, FGF-19, FGF-2, FGF3,FGF-8, FGFR, FGFR-3, Fibrin, Fla., FLIP, Flt-3, Flt-4, Folliclestimulating hormone, Fractalkine, FZD1, FZD2, FZD3, FZD4, FZD5, FZD6,FZD7, FZD8, FZD9, FZD10, G250, Gas 6, GCP-2, GCSF, GD2, GD3, GDF, GDF-1,GDF-3 (Vgr-2), GDF-5 (BMP-14, CDMP-1), GDF-6 (BMP-13, CDMP-2), GDF-7(BMP-12, CDMP-3), GDF-8 (Myostatin), GDF-9, GDF-15 (MIC-1), GDNF, GDNF,GFAP, GFRa-1, GFR-alpha1, GFR-alpha2, GFR-alpha3, GITR, Glucagon, Glut4, glycoprotein IIb/IIIa (GP IIb/IIIa), GM-CSF, gp130, gp72, GRO, Growthhormone releasing factor, Hapten (NP-cap or NIP-cap), HB-EGF, HCC, HCMVgB envelope glycoprotein, HCMV) gH envelope glycoprotein, HCMV UL,Hemopoietic growth factor (HGF), Hep B gp120, heparanase, Her2, Her2/neu(ErbB-2), Her3 (ErbB-3), Her4 (ErbB-4), herpes simplex virus (HSV) gBglycoprotein, HSV gD glycoprotein, HGFA, High molecular weightmelanoma-associated antigen (HMW-MAA), HIV gp120, HIV IIIB gp 120 V3loop, HLA, HLA-DR, HLA-DP, HLA-DQ, CD317/HM1.24, HMFG PEM, HRG, Hrk,human cardiac myosin, human cytomegalovirus (HCMV), human growth hormone(HGH), HVEM, I-309, IAP, ICAM, ICAM-1, ICAM-3, ICE, ICOS, IFNg, Ig, IgAreceptor, IgE, IGF, IGF binding proteins, IGF-1R, IGFBP, IGF-I, IGF-II,IL, IL-1, IL-1R, IL-2, IL-2R, IL-4, IL-4R, IL-5, IL-5R, IL-6, IL-6R,IL-8, IL-9, IL-10, IL-12, IL-13, IL-15, IL-18, IL-18R, IL-23, interferon(INF)-alpha, INF-beta, INF-gamma, Inhibin, iNOS, Insulin A-chain,Insulin B-chain, Insulin-like growth factor 1, integrin alpha2, integrinalpha3, integrin alpha4, integrin alpha4/beta1, integrin alpha4/beta7,integrin alpha5 (alphaV), integrin alpha5/beta1, integrin alpha5/beta3,integrin alpha6, integrin beta1, integrin beta2, interferon gamma,IP-10, I-TAC, JE, Kallikrein 2, Kallikrein 5, Kallikrein 6, Kallikrein11, Kallikrein 12, Kallikrein 14, Kallikrein 15, Kallikrein L1,Kallikrein L2, Kallikrein L3, Kallikrein L4, KC, KDR, KeratinocyteGrowth Factor (KGF), laminin 5, LAMP, LAP, LAP (TGF-1), Latent TGF-1,Latent TGF-1 bp1, LBP, LDGF, LECT2, Lefty, Lewis-Y antigen, Lewis-Yrelated antigen, LFA-1, LFA-3, Lfo, LIF, LIGHT, lipoproteins, LIX, LKN,Lptn, L-Selectin, LT-a, LT-b, LTB4, LTBP-1, Lung surfactant, Luteinizinghormone, Lymphotoxin Beta Receptor, Mac-1, MAdCAM, MAG, MAP2, MARC,MCAM, MCAM, MCK-2, MCP, M-CSF, MDC, Mer, METALLOPROTEASES, MGDFreceptor, MGMT, MHC (HLA-DR), MIF, MIG, MIP, MIP-1-alpha, MK, MMAC1,MMP, MMP-1, MMP-10, MMP-11, MMP-12, MMP-13, MMP-14, MMP-15, MMP-2,MMP-24, MMP-3, MMP-7, MMP-8, MMP-9, MPIF, Mpo, MSK, MSP, mucin (Muc1),MUC18, Muellerian-inhibitin substance, Mug, MuSK, NAIP, NAP, NCAD,N-Cadherin, NCA 90, NCAM, NCAM, Neprilysin, Neurotrophin-3,-4, or -6,Neurturin, Neuronal growth factor (NGF), NGFR, NGF-beta, nNOS, NO, NOS,Npn, NRG-3, NT, NTN, OB, OGG1, OPG, OPN, OSM, OX40L, OX40R, p150, p95,PADPr, Parathyroid hormone, PARC, PARP, PBR, PBSF, PCAD, P-Cadherin,PCNA, PDGF, PDGF, PDK-1, PECAM, PEM, PF4, PGE, PGF, PGI2, PGJ2, PIN,PLA2, placental alkaline phosphatase (PLAP), PIGF, PLP, PP14,Proinsulin, Prorelaxin, Protein C, PS, PSA, PSCA, prostate specificmembrane antigen (PSMA), PTEN, PTHrp, Ptk, PTN, R51, RANK, RANKL,RANTES, RANTES, Relaxin A-chain, Relaxin B-chain, renin, respiratorysyncytial virus (RSV) F, RSV Fgp, Ret, Rheumatoid factors, RLIP76, RPA2,RSK, S100, SCF/KL, SDF-1, SERINE, Serum albumin, sFRP-3, Shh, SIGIRR,SK-1, SLAM, SLPI, SMAC, SMDF, SMOH, SOD, SPARC, Stat, STEAP, STEAP-II,TACE, TACI, TAG-72 (tumor-associated glycoprotein-72), TARC, TCA-3,T-cell receptors (e.g., T-cell receptor alpha/beta), TdT, TECK, TEM1,TEM5, TEM7, TEM8, TERT, testicular PLAP-like alkaline phosphatase, TfR,TGF, TGF-alpha, TGF-beta, TGF-beta Pan Specific, TGF-beta RI (ALK-5),TGF-beta RII, TGF-beta RIIb, TGF-beta RIII, TGF-beta1, TGF-beta2,TGF-beta3, TGF-beta4, TGF-beta5, Thrombin, Thymus Ck-1, Thyroidstimulating hormone, Tie, TIMP, TIQ, Tissue Factor, TMEFF2, Tmpo,TMPRSS2, TNF, TNF-alpha, TNF-alpha beta, TNF-beta2, TNFc, TNF-RI,TNF-RII, TNFRSF10A (TRAIL R1 Apo-2, DR4), TNFRSF10B (TRAIL R2 DR5,KILLER, TRICK-2A, TRICK-B), TNFRSF10C (TRAIL R3 DcR1, LIT, TRID),TNFRSF10D (TRAIL R4 DcR2, TRUNDD), TNFRSF11A (RANK ODF R, TRANCE R),TNFRSF11B (OPG OCIF, TR1), TNFRSF12 (TWEAK R FN14), TNFRSF13B (TACI),TNFRSF13C (BAFF R), TNFRSF14 (HVEM ATAR, HveA, LIGHT R, TR2), TNFRSF16(NGFR p75NTR), TNFRSF17 (BCMA), TNFRSF18 (GITR AITR), TNFRSF19 (TROYTAJ, TRADE), TNFRSF19L (RELT), TNFRSF1A (TNF RI CD120a, p55-60),TNFRSF1B (TNF RII CD120b, p75-80), TNFRSF26 (TNFRH3), TNFRSF3 (LTbR TNFRIII, TNFC R), TNFRSF4 (OX40 ACT35, TXGP1 R), TNFRSF5 (CD40 p50),TNFRSF6 (Fas Apo-1, APT1, CD95), TNFRSF6B (DcR3 M68, TR6), TNFRSF7(CD27), TNFRSF8 (CD30), TNFRSF9 (4-1BB CD137, ILA), TNFRSF21 (DR6),TNFRSF22 (DcTRAIL R2 TNFRH2), TNFRST23 (DcTRAIL R1 TNFRH1), TNFRSF25(DR3 Apo-3, LARD, TR-3, TRAMP, WSL-1), TNFSF10 (TRAIL Apo-2 Ligand,TL2), TNFSF11 (TRANCE/RANK Ligand ODF, OPG Ligand), TNFSF12 (TWEAK Apo-3Ligand, DR3 Ligand), TNFSF13 (APRIL TALL2), TNFSF13B (BAFF BLYS, TALL1,THANK, TNFSF20), TNFSF14 (LIGHT HVEM Ligand, LTg), TNFSF15 (TL1A/VEGI),TNFSF18 (GITR Ligand AITR Ligand, TL6), TNFSF1A (TNF-a Conectin, DIF,TNFSF2), TNFSF1B (TNF-b LTa, TNFSF1), TNFSF3 (LTb TNFC, p33), TNFSF4(0X40 Ligand gp34, TXGP1), TNFSF5 (CD40 Ligand CD154, gp39, HIGM1, IMD3,TRAP), TNFSF6 (Fas Ligand Apo-1 Ligand, APT1 Ligand), TNFSF7 (CD27Ligand CD70), TNFSF8 (CD30 Ligand CD153), TNFSF9 (4-1BB Ligand CD137Ligand), TP-1, t-PA, Tpo, TRAIL, TRAIL R, TRAIL-R1, TRAIL-R2, TRANCE,transferring receptor, TRF, Trk, TROP-2, TSG, TSLP, tumor-associatedantigen CA 125, tumor-associated antigen expressing Lewis Y relatedcarbohydrate, TWEAK, TXB2, Ung, uPAR, uPAR-1, Urokinase, VCAM, VCAM-1,VECAD, VE-Cadherin, VE-cadherin-2, VEFGR-1 (flt-1), VEGF, VEGFR, VEGFR-3(flt-4), VEGI, VIM, Viral antigens, VLA, VLA-1, VLA-4, VNR integrin, vonWillebrands factor, WIF-1, WNT1, WNT2, WNT2B/13, WNT3, WNT3A, WNT4,WNT5A, WNT5B, WNT6, WNT7A, WNT7B, WNT8A, WNT8B, WNT9A, WNT9A, WNT9B,WNT10A, WNT10B, WNT11, WNT16, XCL1, XCL2, XCR1, XCR1, XEDAR, XIAP, XPD,and receptors for hormones and growth factors, etc.

In one embodiment, antigens are those that are expressed on CD32b+cells, e.g., B cell proteins, e.g., one or more proteins of the B cellreceptor complex. Target antigens include, but are not limited to, CD19,CD20, CD21 (CR2), CD22, CD23/FcεRII, FcεRI, (α, β, and γ subunits),CD24/BBA-1/HSA, CD27, CD35 (CR1), CD38, CD40, CD45RA,CD52/CAMPATH-1/HE5, CD72, CD79a (Igα), CD79b (Igβ), IgM (μ), CD80, CD81,CD86, Leu13, HLA-DR, -DP, -DQ, CD138, CD317/HM1.24, CD11a, CD11b, CD11c,CD14, CD68, CD163, CD172a, CD200R, and CD206. In one embodiment, theimmunoglobulins disclosed herein are also specific for a target antigenselected from the group consisting of: IgM (μ), CD19, CD20, CD21, CD22,CD23, CD24, CD35, CD40, CD45RA, CD72, CD79a, CD79b, CD80, CD81, CD86,and HLA-DR. In one embodiment, immunoglobulins disclosed herein are alsospecific for a target antigen selected from the group consisting of: IgM(μ), CD79a, CD79b, CD19, CD21, CD22, CD72, CD81, and Leu13. In oneembodiment, immunoglobulins disclosed herein are also specific for atarget antigen selected from the group consisting of: μ, CD19, CD79a,Cd79b, CD81, and HLA-DR. In another embodiment, immunoglobulinsdisclosed herein are also specific for a target antigen selected fromthe group consisting of: CD22, CD40, and CD72.

In another embodiment, target antigens may include those that are bound,or may be bound, to the surface of B cells. For example, immunoglobulinsdisclosed herein may also target autoimmune antigens (i.e.,autoantigens) or allergens. In one embodiment, autoimmune antigens thatmay be targeted by the immunoglobulins disclosed herein include but arenot limited to double-stranded DNA, platelet antigens, myelin proteinantigen, Sm antigens in snRNPs, islet cell antigen, Rheumatoid factor,and anticitrullinated protein. citrullinated proteins and peptides suchas CCP-1, CCP-2 (cyclical citrullinated peptides), fibrinogen, fibrin,vimentin, fillaggrin, collagen I and II peptides, alpha-enolase,translation initiation factor 4G1, perinuclear factor, keratin, Sa(cytoskeletal protein vimentin), components of articular cartilage suchas collagen II, IX, and XI, circulating serum proteins such as RFs (IgG,IgM), fibrinogen, plasminogen, ferritin, nuclear components such asRA33/hnRNP A2, Sm, eukaryotic trasnlation elogation factor 1 alpha 1,stress proteins such as HSP-65, -70, -90, BiP, inflammatory/immunefactors such as B7-H1, IL-1 alpha, and IL-8, enzymes such ascalpastatin, alpha-enolase, aldolase-A, dipeptidyl peptidase,osteopontin, glucose-6-phosphate isomerase, receptors such as lipocortin1, neutrophil nuclear proteins such as lactoferrin and 25-35kD nuclearprotein, granular proteins such as bactericidal permeability increasingprotein (BPI), elastase, cathepsin G, myeloperoxidase, proteinase 3,platelet antigens, myelin protein antigen, islet cell antigen,rheumatoid factor, histones, ribosomal P proteins, cardiolipin,vimentin, nucleic acids such as dsDNA, ssDNA, and RNA, ribonuclearparticles and proteins such as Sm antigens (including but not limited toSmD's and SmB′/B), U1RNP, A2/B1 hnRNP, Ro (SSA), and La (SSB) antigens.

Fc Variants and Fc Receptor Binding Properties

Immunoglobulins disclosed herein may comprise an Fc variant. An Fcvariant comprises one or more amino acid modifications relative to aparent Fc polypeptide, wherein the amino acid modification(s) provideone or more optimized properties. An Fc variant disclosed herein differsin amino acid sequence from its parent by virtue of at least one aminoacid modification. Thus Fc variants disclosed herein have at least oneamino acid modification compared to the parent. Alternatively, the Fcvariants disclosed herein may have more than one amino acid modificationas compared to the parent, for example from about one to fifty aminoacid modifications, e.g., from about one to ten amino acidmodifications, from about one to about five amino acid modifications,etc. compared to the parent. Thus the sequences of the Fc variants andthose of the parent Fc polypeptide are substantially homologous. Forexample, the variant Fc variant sequences herein will possess about 80%homology with the parent Fc variant sequence, e.g., at least about 90%homology, at least about 95% homology, at least about 98% homology, atleast about 99% homology, etc. Modifications disclosed herein includeamino acid modifications, including insertions, deletions, andsubstitutions. Modifications disclosed herein also include glycoformmodifications. Modifications may be made genetically using molecularbiology, or may be made enzymatically or chemically.

Fc variants disclosed herein are defined according to the amino acidmodifications that compose them. Thus, for example, S267E is an Fcvariant with the substitution S267E relative to the parent Fcpolypeptide. Likewise, S267E/L328F defines an Fc variant with thesubstitutions S267E and L328F relative to the parent Fc polypeptide. Theidentity of the WT amino acid may be unspecified, in which case theaforementioned variant is referred to as 267E/328F. It is noted that theorder in which substitutions are provided is arbitrary, that is to saythat, for example, 267E/328F is the same Fc variant as 328F/267E, and soon. Unless otherwise noted, positions discussed herein are numberedaccording to the EU index or EU numbering scheme (Kabat et al., 1991,Sequences of Proteins of Immunological Interest, 5th Ed., United StatesPublic Health Service, National Institutes of Health, Bethesda, herebyentirely incorporated by reference). The EU index or EU index as inKabat or EU numbering scheme refers to the numbering of the EU antibody(Edelman et al., 1969, Proc Natl Acad Sci USA 63:78-85, hereby entirelyincorporated by reference).

In certain embodiments, the Fc variants disclosed herein are based onhuman IgG sequences, and thus human IgG sequences are used as the “base”sequences against which other sequences are compared, including but notlimited to sequences from other organisms, for example rodent andprimate sequences. Immunoglobulins may also comprise sequences fromother immunoglobulin classes such as IgA, IgE, IgGD, IgGM, and the like.It is contemplated that, although the Fc variants disclosed herein areengineered in the context of one parent IgG, the variants may beengineered in or “transferred” to the context of another, second parentIgG. This is done by determining the “equivalent” or “corresponding”residues and substitutions between the first and second IgG, typicallybased on sequence or structural homology between the sequences of thefirst and second IgGs. In order to establish homology, the amino acidsequence of a first IgG outlined herein is directly compared to thesequence of a second IgG. After aligning the sequences, using one ormore of the homology alignment programs known in the art (for exampleusing conserved residues as between species), allowing for necessaryinsertions and deletions in order to maintain alignment (i.e., avoidingthe elimination of conserved residues through arbitrary deletion andinsertion), the residues equivalent to particular amino acids in theprimary sequence of the first immunoglobulin are defined. Alignment ofconserved residues may conserve 100% of such residues. However,alignment of greater than 75% or as little as 50% of conserved residuesis also adequate to define equivalent residues. Equivalent residues mayalso be defined by determining structural homology between a first andsecond IgG that is at the level of tertiary structure for IgGs whosestructures have been determined. In this case, equivalent residues aredefined as those for which the atomic coordinates of two or more of themain chain atoms of a particular amino acid residue of the parent orprecursor (N on N, CA on CA, C on C and O on O) are within about 0.13nm, after alignment. In another embodiment, equivalent residues arewithin about 0.1 nm after alignment. Alignment is achieved after thebest model has been oriented and positioned to give the maximum overlapof atomic coordinates of non-hydrogen protein atoms of the proteins.Regardless of how equivalent or corresponding residues are determined,and regardless of the identity of the parent IgG in which the IgGs aremade, what is meant to be conveyed is that the Fc variants discovered asdisclosed herein may be engineered into any second parent IgG that hassignificant sequence or structural homology with the Fc variant. Thusfor example, if a variant antibody is generated wherein the parentantibody is human IgG1, by using the methods described above or othermethods for determining equivalent residues, the variant antibody may beengineered in another IgG1 parent antibody that binds a differentantigen, a human IgG2 parent antibody, a human IgA parent antibody, amouse IgG2a or IgG2b parent antibody, and the like. Again, as describedabove, the context of the parent Fc variant does not affect the abilityto transfer the Fc variants disclosed herein to other parent IgGs.

The Fc variants disclosed herein may be optimized for a variety of Fcreceptor binding properties. An Fc variant that is engineered orpredicted to display one or more optimized properties is herein referredto as an “optimized Fc variant”. Properties that may be optimizedinclude but are not limited to enhanced or reduced affinity for an FcγR.In one embodiment, the Fc variants disclosed herein are optimized topossess enhanced affinity for an inhibitory receptor FcγRIIb. In otherembodiments, immunoglobulins disclosed herein provide enhanced affinityfor FcγRIIb, yet reduced affinity for one or more activating FcγRs,including for example FcγRI, FcγRIIa, FcγRIIIa, and/or FcγRIIIb. TheFcγR receptors may be expressed on cells from any organism, includingbut not limited to human, cynomolgus monkeys, and mice. The Fc variantsdisclosed herein may be optimized to possess enhanced affinity for humanFcγRIIb.

By “greater affinity” or “improved affinity” or “enhanced affinity” or“better affinity” than a parent Fc polypeptide, as used herein is meantthat an Fc variant binds to an Fc receptor with a significantly higherequilibrium constant of association (K_(A) or Ka) or lower equilibriumconstant of dissociation (K_(D) or Kd) than the parent Fc polypeptidewhen the amounts of variant and parent polypeptide in the binding assayare essentially the same. For example, the Fc variant with improved Fcreceptor binding affinity may display from about 5 fold to about 1000fold, e.g. from about 10 fold to about 500 fold improvement in Fcreceptor binding affinity compared to the parent Fc polypeptide, whereFc receptor binding affinity is determined, for example, by the bindingmethods disclosed herein, including but not limited to Biacore, by oneskilled in the art. Accordingly, by “reduced affinity” as compared to aparent Fc polypeptide as used herein is meant that an Fc variant bindsan Fc receptor with significantly lower K_(A) or higher K_(D) than theparent Fc polypeptide. Greater or reduced affinity can also be definedrelative to an absolute level of affinity. For example, according to thedata herein, WT (native) IgG1 binds FcγRIIb with an affinity of about1.5 μM, or about 1500 nM. Furthermore, some Fc variants described hereinbind FcγRIIb with an affinity about 10-fold greater to WT IgG1. Asdisclosed herein, greater or enhanced affinity means having a K_(D)lower than about 100 nM, for example between about 10 nM—about 100 nM,between about 1—about 100 nM, or less than about 1 nM.

In one embodiment, the Fc variants provide selectively enhanced affinityto FcγRIIb relative to one or more activating receptors. Selectivelyenhanced affinity means either that the Fc variant has improved affinityfor FcγRIIb relative to the activating receptor(s) as compared to theparent Fc polypeptide but has reduced affinity for the activatingreceptor(s) as compared to the parent Fc polypeptide, or it means thatthe Fc variant has improved affinity for both FcγRIIb and activatingreceptor(s) as compared to the parent Fc polypeptide, however theimprovement in affinity is greater for FcγRIIb than it is for theactivating receptor(s). In alternate embodiments, the Fc variants reduceor ablate binding to one or more activating FcγRs, reduce or ablatebinding to one or more complement proteins, reduce or ablate one or moreFcγR-mediated effector functions, and/or reduce or ablate one or morecomplement-mediated effector functions.

The presence of different polymorphic forms of FcγRs provides yetanother parameter that impacts the therapeutic utility of the Fcvariants disclosed herein. Whereas the specificity and selectivity of agiven Fc variant for the different classes of FcγRs significantlyaffects the capacity of an Fc variant to target a given antigen fortreatment of a given disease, the specificity or selectivity of an Fcvariant for different polymorphic forms of these receptors may in partdetermine which research or pre-clinical experiments may be appropriatefor testing, and ultimately which patient populations may or may notrespond to treatment. Thus the specificity or selectivity of Fc variantsdisclosed herein to Fc receptor polymorphisms, including but not limitedto FcγRIIa, FcγRIIIa, and the like, may be used to guide the selectionof valid research and pre-clinical experiments, clinical trial design,patient selection, dosing dependence, and/or other aspects concerningclinical trials.

Fc variants disclosed herein may comprise modifications that modulateinteraction with Fc receptors other than FcγRs, including but notlimited to complement proteins, FcRn, and Fc receptor homologs (FcRHs).FcRHs include but are not limited to FcRH1, FcRH2, FcRH3, FcRH4, FcRH5,and FcRH6 (Davis et al., 2002, Immunol. Reviews 190:123-136).

An important parameter that determines the most beneficial selectivityof a given Fc variant to treat a given disease is the context of the Fcvariant. Thus the Fc receptor selectivity or specificity of a given Fcvariant will provide different properties depending on whether itcomposes an antibody, Fc fusion, or Fc variants with a coupled fusionpartner. In one embodiment, an Fc receptor specificity of the Fc variantdisclosed herein will determine its therapeutic utility. The utility ofa given Fc variant for therapeutic purposes will depend on the epitopeor form of the target antigen and the disease or indication beingtreated. For some targets and indications, greater FcγRIIb affinity andreduced activating FcγR-mediated effector functions may be beneficial.For other target antigens and therapeutic applications, it may bebeneficial to increase affinity for FcγRIIb, or increase affinity forboth FcγRIIb and activating receptors.

Inhibitory Properties and Methods of Inhibiting CD32b⁺ Cells

Target antigens of immunoglobulins disclosed herein may be expressed ona variety of cell types. In some embodiments, immunoglobulins disclosedherein are specific for antigens expressed on CD32b+ cells. Cell typesthat may be targeted by the immunoglobulins disclosed herein include,but are not limited to, B cells, plasma cells, dendritic cells,macrophages, neutrophils, mast cells, basophils, and eosinophils. Inalternative embodiments, the immunoglobulins disclosed herein mayinhibit CD32b+ cells by targeting an antigen not expressed on CD32b+cells. In some embodiments, target antigens include those that are notexpressed by CD32b+ cells, but may be bound to CD32b+ cells, e.g., viathe BCR. For example, in certain embodiments, the immunoglobulins maytarget an autoimmune antigen or allergen. Autoimmune antigens that maybe targeted by the immunoglobulins disclosed herein include but are notlimited to citrullinated proteins and peptides such as CCP-1, CCP-2(cyclical citrullinated peptides), fibrinogen, fibrin, vimentin,fillaggrin, collagen I and II peptides, alpha-enolase, translationinitiation factor 4G1, perinuclear factor, keratin, Sa (cytoskeletalprotein vimentin), components of articular cartilage such as collagenII, IX, and XI, circulating serum proteins such as RFs (IgG, IgM),fibrinogen, plasminogen, ferritin, nuclear components such as RA33/hnRNPA2, Sm, eukaryotic trasnlation elogation factor 1 alpha 1, stressproteins such as HSP-65, -70, -90, BiP, inflammatory/immune factors suchas B7-H1, IL-1 alpha, and IL-8, enzymes such as calpastatin,alpha-enolase, aldolase-A, dipeptidyl peptidase, osteopontin,glucose-6-phosphate isomerase, receptors such as lipocortin 1,neutrophil nuclear proteins such as lactoferrin and 25-35kD nuclearprotein, granular proteins such as bactericidal permeability increasingprotein (BPI), elastase, cathepsin G, myeloperoxidase, proteinase 3,platelet antigens, myelin protein antigen, islet cell antigen,rheumatoid factor, histones, ribosomal P proteins, cardiolipin,vimentin, nucleic acids such as dsDNA, ssDNA, and RNA, ribonuclearparticles and proteins such as Sm antigens (including but not limited toSm D's and SmB′/B), U1RNP, A2/B1 hnRNP, Ro (SSA), and La (SSB) antigens.

Disclosed herein are methods of inhibiting CD32b+ cells. Without beinglimited thereto, FIG. 3 is a schematic representation of a proposedmechanism by which immunoglobulins disclosed herein inhibit CD32b+ cells(See also Example 3; see also FIG. 3). Accordingly, disclosed herein aremethods of inhbiting CD32b+ cells comprising contacting a CD32b+ cellwith an immunoglobulin comprising an Fc region with enhanced affinity toFcγRIIb. In one embodiment, the immunoglobulin binds at least two B cellproteins, e.g., at least to proteins bound to the surface B cells. Inone embodiment, the first of said B cell proteins is FcγRIIb. In aanother embodiment, the second of said B cell proteins is part of the Bcell receptor (BCR) complex, which may include an antigen bound to BCR.In another embodiment, the second of said B cell proteins is notinvolved directly in antigen recognition. In another embodiment, saidthe second of said B cell proteins is expressed on the surface of the Bcell, but is not part of the B cell receptor. Nonlimiting examples ofthe second of said B cell proteins include BCR proteins (e.g., IgM (μ),CD79a, CD79b, CD19, CD21, CD22, CD72, CD81, Leu13, etc.), antigens boundto the BCR (e.g., autoantigens, allergens, etc.), or other proteinsbound to the surface of B cells (e.g., CD20, CD23, CD24, CD35, CD40,CD45RA, CD80, CD86, HLA-DR, etc.). In some embodiments, theimmunoglobulins inhibit release of calcium from the B cells upon theirstimulation through the B cell receptor. In another embodiment, animmunoglobulin disclosed herein binds at least two B cell proteins onthe surface of the same B cell (see, e.g., FIG. 3).

Modifications for Optimizing Inhibitory Function

Disclosed herein is directed to immunoglobulins comprisingmodifications, wherein said modifications alter affinity to the FcγRIIbreceptor, and/or alter the ability of the immunoglobulin to mediate oneor more FcγRIIb-mediated effector functions. Modifications of theinvention include amino acid modifications and glycoform modifications.

Amino Acid Modifications

As described herein (see, e.g., Example 9), simultaneous high affinitycoengagement of cognate BCR and FcγRIIb may be used to inhibit FcγRIIb+cells. Such coengagment may occur via the use of an immunoglobulindescribed herein, e.g., an immunoglobulin used to coengage both FcγRIIbvia its Fc region, and a target antigen on the surface of the FcγRIIb+cell (e.g., one or more cognate BCR proteins and/or an antigen bound tocognate BCR) via its Fv region. Amino acid modifications at heavy chainconstant region positions: 234, 235, 236, 237, 239, 265, 266, 267, 268,298, 325, 326, 327, 328, 329, 330, 331 and 332 allow modification ofimmunoglobulin FcγRIIb binding properties, effector function, andpotentially clinical properties of antibodies

In one embodiment, immunoglobulins that bind FcγRIIb+ cells and coengagea target antigen on the cell's surface and an FcγRIIb on cell's surfacedisclosed herein may be variant immunoglobulins relative to a parentimmunoglobulin. In one embodiment, the variant immunoglobulin comprisesa variant Fc region, wherein said variant Fc region comprises one ormore (e.g., two or more) modification(s) compared to a parent Fc region,wherein said modification(s) are at positions selected from the groupconsisting of 234, 235, 236, 237, 239, 265, 266, 267, 268, 298, 325,326, 327, 328, 329, 330, 331, and 332, wherein numbering is according tothe EU index. In one embodiment, the variant immunoglobulin comprises avariant Fc region, wherein said variant Fc region comprises one or more(e.g., two or more) modification(s) compared to a parent Fc region,wherein said modification(s) are at positions selected from the groupconsisting of 234, 235, 236, 237, 239, 266, 267, 268, 325, 326, 327,328, and 332, according to the EU index. In one embodiment, the variantimmunoglobulin comprises a variant Fc region, wherein said variant Fcregion comprises one or more (e.g., two or more) modification(s)compared to a parent Fc region, wherein said modification(s) are atpositions selected from the group consisting of 235, 236, 239, 266, 267,268, and 328, according to the EU index.

In one embodiment, said modification(s) is at least one substitution(e.g., one or more substitution(s), two or more substitution(s), etc.)selected from the group consisting of 234F, 234G, 234I, 234K, 234N,234P, 234Q, 234S, 234V, 234W, 234Y, 234D, 234E, 235A, 235E, 235H, 235I,235N, 235P, 235Q, 235R, 235S, 235W, 235Y, 235D, 235F, 235T, 236D, 236F,236H, 236I, 236K, 236L, 236M, 236P, 236Q, 236R, 236S, 236T, 236V, 236W,236Y, 236A, 236E, 236N, 237A, 237E, 237H, 237K, 237L, 237P, 237Q, 237S,237V, 237Y, 237D, 237N, 239D, 239E, 239N, 239Q, 265E, 266D, 266I, 266M,267A, 267D, 267E, 267G, 268D, 268E, 268N, 268Q, 298D, 298E, 298L, 298M,298Q, 325L, 326A, 326E, 326W, 326D, 327D, 327G, 327L, 327N, 327Q, 327E,328E, 328F, 328Y, 328H, 328I, 328Q, 328W, 329E, 330D, 330H, 330K, 330S,331S, and 332E, wherein numbering is according to an EU index. In oneembodiment, said modification(s) is at least one substitution (e.g., oneor more substitution(s), two or more substitution(s), etc.) selectedfrom the group consisting of 234N, 234F, 234D, 234E, 234W, 235Q, 235R,235W, 235Y, 235D, 235F, 235T, 236D, 236H, 236I, 236L, 236S, 236Y, 236E,236N, 237H, 237L, 237D, 237N, 239D, 239N, 239E, 266I, 266M, 267A, 267D,267E, 267G, 268D, 268E, 268N, 268Q, 298E, 298L, 298M, 298Q, 325L, 326A,326E, 326W, 326D, 327D, 327L, 327E, 328E, 328F, 328Y, 328H, 328I, 328Q,328W, 330D, 330H, 330K, and 332E, wherein numbering is according to anEU index. In one embodiment, said modification(s) is at least onesubstitution (e.g., one or more substitution(s), two or moresubstitution(s), etc.) selected from the group consisting of 234D, 234E,234W, 235D, 235F, 235R, 235Y, 236D, 236N, 237D, 237N, 239D, 239E, 266M,267D, 267E, 268D, 268E, 327D, 327E, 328F, 328W, 328Y, and 332E, whereinnumbering is according to an EU index. In one embodiment, saidmodification(s) is at least one substitution (e.g., one or moresubstitution(s), two or more substitution(s), etc.) selected from thegroup consisting of 235Y, 236D, 239D, 266M, 267E, 268D, 268E, 328F,328W, and 328Y, wherein numbering is according to an EU index.

In one embodiment, said modification(s) is at least two modifications(e.g., a combination of modifications) at positions selected from thegroup consisting of 234/239, 234/267, 234/328, 235/236, 235/239,235/267, 235/268, 235/328, 236/239, 236/267, 236/268, 236/328, 237/267,239/267, 239/268, 239/327, 239/328, 239/332, 266/267, 267/268, 267/325,267/327, 267/328, 267/332, 268/327, 268/328, 268/332, 326/328, 327/328,and 328/332, wherein numbering is according to an EU index. In oneembodiment, said modification(s) is at least two modifications (e.g., acombination of modifications) at positions selected from the groupconsisting of 235/267, 236/267, 239/268, 239/267, 267/268, and 267/328,wherein numbering is according to an EU index. In one embodiment, saidmodification(s) is at least two substitutions (e.g., a combination ofsubstitutions) selected from the group consisting of 234D/267E,234E/267E, 234F/267E, 234E/328F, 234W/239D, 234W/239E, 234W/267E,234W/328Y, 235D/267E, 235D/328F, 235F/239D, 235F/267E, 235F/328Y,235Y/236D, 235Y/239D, 235Y/267D, 235Y/267E, 235Y/268E, 235Y/328F,236D/239D, 236D/267E, 236D/268E, 236D/328F, 236N/267E, 237D/267E,237N/267E, 239D/267D, 239D/267E, 239D/268D, 239D/268E, 239D/327D,239D/328F, 239D/328W, 239D/328Y, 239D/332E, 239E/267E, 266M/267E,267D/268E, 267E/268D, 267E/268E, 267E/325L, 267E/327D, 267E/327E,267E/328F, 267E/328I, 267E/328Y, 267E/332E, 268D/327D, 268D/328F,268D/328W, 268D/328Y, 268D/332E, 268E/328F, 268E/328Y, 327D/328Y,328F/332E, 328W/332E, and 328Y/332E, wherein numbering is according toan EU index.

In one embodiment, said modification(s) result in at least one of thefollowing substitutions, or combinations of substitutions: 234F/236N,234F/236D, 236A/237A, 236S/237A, 235D/239D, 234D/267E, 234E/267E,234F/267E, 235D/267E, 235F/267E, 235S/267E, 235T/267E, 235Y/267D,235Y/267E, 236D/267E, 236E/267E, 236N/267E, 237D/267E, 237N/267E,239D/267D, 239D/267E, 266M/267E, 234E/268D, 236D/268D, 239D/268D,267D/268D, 267D/268E, 267E/268D, 267E/268E, 267E/325L, 267D/327D,267D/327E, 267E/327D, 267E/327E, 268D/327D, 239D/328Y, 267E/328F,267E/328H, 267E/328I, 267E/328Q, 267E/328Y, 268D/328Y, 239D/332E,328Y/332E, 234D/236N/267E, 235Y/236D/267E, 234W/239E/267E,235Y/239D/267E, 236D/239D/267E, 235Y/267E/268E, 236D/267E/268E,239D/267E/268E, 234W/239D/328Y, 235F/239D/328Y, 234E/267E/328F,235D/267E/328F, 235Y/267E/328F, 236D/267E/328F, 239D/267A/328Y,239D/267E/328F, 234W/268D/328Y, 235F/268D/328Y, 239D/268D/328F,239D/268D/328W, 239D/268D/328Y, 239D/268E/328Y, 267A/268D/328Y,267E/268E/328F, 239D/326D/328Y, 268D/326D/328Y, 239D/327D/328Y,268D/327D/328Y, 239D/267E/332E, 234W/328Y/332E, 235F/328Y/332E,239D/328F/332E, 239D/328Y/332E, 267A/328Y/332E, 268D/328F/332E,268D/328W/332E, 268D/328Y/332E, 268E/328Y/332E, 326D/328Y/332E,327D/328Y/332E, 234W/236D/239E/267E, 239D/268D/328F/332E,239D/268D/328W/332E, and 239D/268D/328Y/332E, wherein numbering isaccording to an EU index. In one embodiment, said modification(s) resultin at least one of the following substitutions, or combinations ofsubstitutions: 266D, 234F/236N, 234F/236D, 236A/237A, 236S/237A,235D/239D, 234D/267E, 234E/267E, 234F/267E, 235D/267E, 235F/267E,235S/267E, 235T/267E, 235Y/267D, 236D/267E, 236E/267E, 236N/267E,237D/267E, 237N/267E, 266M/267E, 234E/268D, 236D/268D, 267D/268D,267D/268E, 267E/268D, 267E/268E, 267E/325L, 267D/327D, 267D/327E,267E/327E, 268D/327D, 239D/328Y, 267E/328F, 267E/328H, 267E/328I,267E/328Q, 267E/328Y, 268D/328Y, 234D/236N/267E, 235Y/236D/267E,234W/239E/267E, 235Y/239D/267E, 236D/239D/267E, 235Y/267E/268E,236D/267E/268E, 234W/239D/328Y, 235F/239D/328Y, 234E/267E/328F,235D/267E/328F, 235Y/267E/328F, 236D/267E/328F, 239D/267A/328Y,239D/267E/328F, 234W/268D/328Y, 235F/268D/328Y, 239D/268D/328F,239D/268D/328W, 239D/268D/328Y, 239D/268E/328Y, 267A/268D/328Y,267E/268E/328F, 239D/326D/328Y, 268D/326D/328Y, 239D/327D/328Y,268D/327D/328Y, 234W/328Y/332E, 235F/328Y/332E, 239D/328F/332E,239D/328Y/332E, 267A/328Y/332E, 268D/328F/332E, 268D/328W/332E,268D/328Y/332E, 268E/328Y/332E, 326D/328Y/332E, 327D/328Y/332E,234W/236D/239E/267E, 239D/268D/328F/332E, 239D/268D/328W/332E, and239D/268D/328Y/332E, wherein numbering is according to an EU index. Inone embodiment, said modification(s) result in at least one of thefollowing substitutions, or combinations of substitutions: 234N, 235Q,235R, 235W, 235Y, 236D, 236H, 236I, 236L, 236S, 236Y, 237H, 237L, 239D,239N, 266I, 266M, 267A, 267D, 267E, 267G, 268D, 268E, 268N, 268Q, 298E,298L, 298M, 298Q, 326A, 326E, 326W, 327D, 327L, 328E, 328F, 330D, 330H,330K, 234F/236N, 234F/236D, 235D/239D, 234D/267E, 234E/267E, 234F/267E,235D/267E, 235F/267E, 235T/267E, 235Y/267D, 235Y/267E, 236D/267E,236E/267E, 236N/267E, 237D/267E, 237N/267E, 239D/267D, 239D/267E,266M/267E, 234E/268D, 236D/268D, 239D/268D, 267D/268D, 267D/268E,267E/268D, 267E/268E, 267E/325L, 267D/327D, 267D/327E, 267E/327D,267E/327E, 268D/327D, 239D/328Y, 267E/328F, 267E/328H, 267E/328I,267E/328Q, 267E/328Y, 268D/328Y, 239D/332E, 328Y/332E, 234D/236N/267E,235Y/236D/267E, 234W/239E/267E, 235Y/239D/267E, 236D/239D/267E,235Y/267E/268E, 236D/267E/268E, 239D/267E/268E, 234W/239D/328Y,235F/239D/328Y, 234E/267E/328F, 235D/267E/328F, 235Y/267E/328F,236D/267E/328F, 239D/267A/328Y, 239D/267E/328F, 234W/268D/328Y,235F/268D/328Y, 239D/268D/328F, 239D/268D/328W, 239D/268D/328Y,239D/268E/328Y, 267A/268D/328Y, 267E/268E/328F, 239D/326D/328Y,268D/326D/328Y, 239D/327D/328Y, 268D/327D/328Y, 239D/267E/332E,234W/328Y/332E, 235F/328Y/332E, 239D/328F/332E, 239D/328Y/332E,267A/328Y/332E, 268D/328F/332E, 268D/328W/332E, 268D/328Y/332E,268E/328Y/332E, 326D/328Y/332E, 327D/328Y/332E, 234W/236D/239E/267E,239D/268D/328F/332E, 239D/268D/328W/332E, and 239D/268D/328Y/332E

In one embodiment, said modification(s) result in at least one of thefollowing substitutions, or combinations of substitutions: 235Y/267E,236D/267E, 239D/268D, 239D/267E, 267E/268D, 267E/268E, and 267E/328F,wherein numbering is according to an EU index.

In some embodiments, antibodies may comprise isotypic modifications,that is, modifications in a parent IgG to the amino acid type in analternate IgG. For example as illustrated in FIG. 1, an IgG1/IgG3 hybridvariant may be constructed by substituting IgG1 positions in the CH2and/or CH3 region with the amino acids from IgG3 at positions where thetwo isotypes differ. Thus a hybrid variant IgG antibody may beconstructed that comprises one or more substitutions selected from thegroup consisting of: 274Q, 276K, 300F, 339T, 356E, 358M, 384S, 392N,397M, 422I, 435R, and 436F. In other embodiments of the invention, anIgG1/IgG2 hybrid variant may be constructed by substituting IgG2positions in the CH2 and/or CH3 region with amino acids from IgG1 atpositions where the two isotypes differ. Thus a hybrid variant IgGantibody may be constructed that comprises one or more modificationsselected from the group consisting of 233E, 234L, 235L, -236G (referringto an insertion of a glycine at position 236), and 327A.

Means for Optimizing Effector Function

Described herein are immunoglobulins comprising means for alter affinityto the FcγRIIb receptor, and/or alter the ability of the immunoglobulinto mediate one or more FcγRIIb-mediated effector functions. Means of theinvention include amino acid modifications (e.g., positional means foroptimizing effector function, substitutional means for optimizingeffector function, etc.) and glycoform modifications (e.g., means forglycoform modifications).

Amino Acid Modifications

As described herein, positional means for optimizing effector functioninclude but is not limited to, modification of an amino acid at one ormore heavy chain constant region positions (e.g., at positions: 234,235, 236, 237, 239, 265, 266, 267, 268, 298, 325, 326, 327, 328, 329,330, 331, and 332) which allow modification of immunoglobulin FcγRIIbbinding properties, effector function, and potentially clinicalproperties of antibodies.

In particular, substitutional means for optimizing FcγRIIb effectorfunctions, e.g., by altering affinity to FcγRIIb, include, but is notlimited to, a substitution of an amino acid at one or more heavy chainconstant region positions, e.g., one or more of the amino acidsubstitutions in the following heavy chain constant region positions:234, 235, 236, 237, 239, 265, 266, 267, 268, 298, 325, 326, 327, 328,329, 330, 331, and 332, wherein numbering is according to the EU index.In one embodiment, substitutional means include at least one (e.g., twoor more) substitution(s) compared to a parent Fc region, wherein saidmodification(s) are at positions selected from the group consisting of234, 235, 236, 237, 239, 266, 267, 268, 325, 326, 327, 328, and 332,according to the EU index. In one embodiment, substitional means includeone or more (e.g., two or more) substitions(s) at positions selectedfrom the group consisting of 235, 236, 239, 266, 267, 268, and 328,according to the EU index.

In one embodiment, said substitional means is at least one substitution(e.g., one or more substitution(s), two or more substitution(s), etc.)selected from the group consisting of 234F, 234G, 234I, 234K, 234N,234P, 234Q, 234S, 234V, 234W, 234Y, 234D, 234E, 235A, 235E, 235H, 235I,235N, 235P, 235Q, 235R, 235S, 235W, 235Y, 235D, 235F, 235T, 236D, 236F,236H, 236I, 236K, 236L, 236M, 236P, 236Q, 236R, 236S, 236T, 236V, 236W,236Y, 236A, 236E, 236N, 237A, 237E, 237H, 237K, 237L, 237P, 237Q, 237S,237V, 237Y, 237D, 237N, 239D, 239E, 239N, 239Q, 265E, 266D, 266I, 266M,267A, 267D, 267E, 267G, 268D, 268E, 268N, 268Q, 298D, 298E, 298L, 298M,298Q, 325L, 326A, 326E, 326W, 326D, 327D, 327G, 327L, 327N, 327Q, 327E,328E, 328F, 328Y, 328H, 328I, 328Q, 328W, 329E, 330D, 330H, 330K, 330S,331S, and 332E, wherein numbering is according to an EU index. In oneembodiment, said substitional means is at least one substitution (e.g.,one or more substitution(s), two or more substitution(s), etc.) selectedfrom the group consisting of 234N, 234F, 234D, 234E, 234W, 235Q, 235R,235W, 235Y, 235D, 235F, 235T, 236D, 236H, 236I, 236L, 236S, 236Y, 236E,236N, 237H, 237L, 237D, 237N, 239D, 239N, 239E, 266I, 266M, 267A, 267D,267E, 267G, 268D, 268E, 268N, 268Q, 298E, 298L, 298M, 298Q, 325L, 326A,326E, 326W, 326D, 327D, 327L, 327E, 328E, 328F, 328Y, 328H, 328I, 328Q,328W, 330D, 330H, 330K, and 332E, wherein numbering is according to anEU index. In one embodiment, said substitional means is at least onesubstitution (e.g., one or more substitution(s), two or moresubstitution(s), etc.) selected from the group consisting of 234D, 234E,234W, 235D, 235F, 235R, 235Y, 236D, 236N, 237D, 237N, 239D, 239E, 266M,267D, 267E, 268D, 268E, 327D, 327E, 328F, 328W, 328Y, and 332E, whereinnumbering is according to an EU index. In one embodiment, saidsubstitional means is at least one substitution (e.g., one or moresubstitution(s), two or more substitution(s), etc.) selected from thegroup consisting of 235Y, 236D, 239D, 266M, 267E, 268D, 268E, 328F,328W, and 328Y, wherein numbering is according to an EU index.

In one embodiment, said substitional means is at least two substitutions(e.g., a combination of modifications) at positions selected from thegroup consisting of 234/239, 234/267, 234/328, 235/236, 235/239,235/267, 235/268, 235/328, 236/239, 236/267, 236/268, 236/328, 237/267,239/267, 239/268, 239/327, 239/328, 239/332, 266/267, 267/268, 267/325,267/327, 267/328, 267/332, 268/327, 268/328, 268/332, 326/328, 327/328,and 328/332, wherein numbering is according to an EU index. In oneembodiment, said substitional means is at least two substitutions (e.g.,a combination of modifications) at positions selected from the groupconsisting of 235/267, 236/267, 239/268, 239/267, 267/268, and 267/328,wherein numbering is according to an EU index. In one embodiment, saidsubstitional means is at least two substitutions (e.g., a combination ofsubstitutions) selected from the group consisting of 234D/267E,234E/267E, 234F/267E, 234E/328F, 234W/239D, 234W/239E, 234W/267E,234W/328Y, 235D/267E, 235D/328F, 235F/239D, 235F/267E, 235F/328Y,235Y/236D, 235Y/239D, 235Y/267D, 235Y/267E, 235Y/268E, 235Y/328F,236D/239D, 236D/267E, 236D/268E, 236D/328F, 236N/267E, 237D/267E,237N/267E, 239D/267D, 239D/267E, 239D/268D, 239D/268E, 239D/327D,239D/328F, 239D/328W, 239D/328Y, 239D/332E, 239E/267E, 266M/267E,267D/268E, 267E/268D, 267E/268E, 267E/325L, 267E/327D, 267E/327E,267E/328F, 267E/328I, 267E/328Y, 267E/332E, 268D/327D, 268D/328F,268D/328W, 268D/328Y, 268D/332E, 268E/328F, 268E/328Y, 327D/328Y,328F/332E, 328W/332E, and 328Y/332E, wherein numbering is according toan EU index.

In one embodiment, said substitional means result in at least one of thefollowing substitutions, or combinations of substitutions: 234F/236N,234F/236D, 236A/237A, 236S/237A, 235D/239D, 234D/267E, 234E/267E,234F/267E, 235D/267E, 235F/267E, 235S/267E, 235T/267E, 235Y/267D,235Y/267E, 236D/267E, 236E/267E, 236N/267E, 237D/267E, 237N/267E,239D/267D, 239D/267E, 266M/267E, 234E/268D, 236D/268D, 239D/268D,267D/268D, 267D/268E, 267E/268D, 267E/268E, 267E/325L, 267D/327D,267D/327E, 267E/327D, 267E/327E, 268D/327D, 239D/328Y, 267E/328F,267E/328H, 267E/328I, 267E/328Q, 267E/328Y, 268D/328Y, 239D/332E,328Y/332E, 234D/236N/267E, 235Y/236D/267E, 234W/239E/267E,235Y/239D/267E, 236D/239D/267E, 235Y/267E/268E, 236D/267E/268E,239D/267E/268E, 234W/239D/328Y, 235F/239D/328Y, 234E/267E/328F,235D/267E/328F, 235Y/267E/328F, 236D/267E/328F, 239D/267A/328Y,239D/267E/328F, 234W/268D/328Y, 235F/268D/328Y, 239D/268D/328F,239D/268D/328W, 239D/268D/328Y, 239D/268E/328Y, 267A/268D/328Y,267E/268E/328F, 239D/326D/328Y, 268D/326D/328Y, 239D/327D/328Y,268D/327D/328Y, 239D/267E/332E, 234W/328Y/332E, 235F/328Y/332E,239D/328F/332E, 239D/328Y/332E, 267A/328Y/332E, 268D/328F/332E,268D/328W/332E, 268D/328Y/332E, 268E/328Y/332E, 326D/328Y/332E,327D/328Y/332E, 234W/236D/239E/267E, 239D/268D/328F/332E,239D/268D/328W/332E, and 239D/268D/328Y/332E, wherein numbering isaccording to an EU index. In one embodiment, said substitional meansresult in at least one of the following substitutions, or combinationsof substitutions: 266D, 234F/236N, 234F/236D, 236A/237A, 236S/237A,235D/239D, 234D/267E, 234E/267E, 234F/267E, 235D/267E, 235F/267E,235S/267E, 235T/267E, 235Y/267D, 236D/267E, 236E/267E, 236N/267E,237D/267E, 237N/267E, 266M/267E, 234E/268D, 236D/268D, 267D/268D,267D/268E, 267E/268D, 267E/268E, 267E/325L, 267D/327D, 267D/327E,267E/327E, 268D/327D, 239D/328Y, 267E/328F, 267E/328H, 267E/328I,267E/328Q, 267E/328Y, 268D/328Y, 234D/236N/267E, 235Y/236D/267E,234W/239E/267E, 235Y/239D/267E, 236D/239D/267E, 235Y/267E/268E,236D/267E/268E, 234W/239D/328Y, 235F/239D/328Y, 234E/267E/328F,235D/267E/328F, 235Y/267E/328F, 236D/267E/328F, 239D/267A/328Y,239D/267E/328F, 234W/268D/328Y, 235F/268D/328Y, 239D/268D/328F,239D/268D/328W, 239D/268D/328Y, 239D/268E/328Y, 267A/268D/328Y,267E/268E/328F, 239D/326D/328Y, 268D/326D/328Y, 239D/327D/328Y,268D/327D/328Y, 234W/328Y/332E, 235F/328Y/332E, 239D/328F/332E,239D/328Y/332E, 267A/328Y/332E, 268D/328F/332E, 268D/328W/332E,268D/328Y/332E, 268E/328Y/332E, 326D/328Y/332E, 327D/328Y/332E,234W/236D/239E/267E, 239D/268D/328F/332E, 239D/268D/328W/332E, and239D/268D/328Y/332E, wherein numbering is according to an EU index. Inone embodiment, said substitional means result in at least one of thefollowing substitutions, or combinations of substitutions: 234N, 235Q,235R, 235W, 235Y, 236D, 236H, 236I, 236L, 236S, 236Y, 237H, 237L, 239D,239N, 266I, 266M, 267A, 267D, 267E, 267G, 268D, 268E, 268N, 268Q, 298E,298L, 298M, 298Q, 326A, 326E, 326W, 327D, 327L, 328E, 328F, 330D, 330H,330K, 234F/236N, 234F/236D, 235D/239D, 234D/267E, 234E/267E, 234F/267E,235D/267E, 235F/267E, 235T/267E, 235Y/267D, 235Y/267E, 236D/267E,236E/267E, 236N/267E, 237D/267E, 237N/267E, 239D/267D, 239D/267E,266M/267E, 234E/268D, 236D/268D, 239D/268D, 267D/268D, 267D/268E,267E/268D, 267E/268E, 267E/325L, 267D/327D, 267D/327E, 267E/327D,267E/327E, 268D/327D, 239D/328Y, 267E/328F, 267E/328H, 267E/328I,267E/328Q, 267E/328Y, 268D/328Y, 239D/332E, 328Y/332E, 234D/236N/267E,235Y/236D/267E, 234W/239E/267E, 235Y/239D/267E, 236D/239D/267E,235Y/267E/268E, 236D/267E/268E, 239D/267E/268E, 234W/239D/328Y,235F/239D/328Y, 234E/267E/328F, 235D/267E/328F, 235Y/267E/328F,236D/267E/328F, 239D/267A/328Y, 239D/267E/328F, 234W/268D/328Y,235F/268D/328Y, 239D/268D/328F, 239D/268D/328W, 239D/268D/328Y,239D/268E/328Y, 267A/268D/328Y, 267E/268E/328F, 239D/326D/328Y,268D/326D/328Y, 239D/327D/328Y, 268D/327D/328Y, 239D/267E/332E,234W/328Y/332E, 235F/328Y/332E, 239D/328F/332E, 239D/328Y/332E,267A/328Y/332E, 268D/328F/332E, 268D/328W/332E, 268D/328Y/332E,268E/328Y/332E, 326D/328Y/332E, 327D/328Y/332E, 234W/236D/239E/267E,239D/268D/328F/332E, 239D/268D/328W/332E, and 239D/268D/328Y/332E

In one embodiment, said substitional means result in at least one of thefollowing substitutions, or combinations of substitutions: 235Y/267E,236D/267E, 239D/268D, 239D/267E, 267E/268D, 267E/268E, and 267E/328F,wherein numbering is according to an EU index.

In some embodiments of the invention, immunoglobulin may comprise meansfor isotypic modifications, that is, modifications in a parent IgG tothe amino acid type in an alternate IgG. For example as illustrated inFIG. 2A, an IgG1/IgG3 hybrid variant may be constructed by asubstitutional means for substituting IgG1 positions in the CH2 and/orCH3 region with the amino acids from IgG3 at positions where the twoisotypes differ. Thus a hybrid variant IgG antibody may be constructedthat comprises one or more substitutional means, e.g., 274Q, 276K, 300F,339T, 356E, 358M, 384S, 392N, 397M, 422I, 435R, and 436F. In otherembodiments of the invention, an IgG1/IgG2 hybrid variant may beconstructed by a substitutional means for substituting IgG2 positions inthe CH2 and/or CH3 region with amino acids from IgG1 at positions wherethe two isotypes differ. Thus a hybrid variant IgG antibody may beconstructed that comprises one or more substitutional means, e.g., oneor more of the following amino acid substations: 233E, 234L, 235L, -236G(referring to an insertion of a glycine at position 236), and 327A.

Glycoform Modifications

Many polypeptides, including antibodies, are subjected to a variety ofpost-translational modifications involving carbohydrate moieties, suchas glycosylation with oligosaccharides. There are several factors thatcan influence glycosylation. The species, tissue and cell type have allbeen shown to be important in the way that glycosylation occurs. Inaddition, the extracellular environment, through altered cultureconditions such as serum concentration, may have a direct effect onglycosylation (Lifely et al., 1995, Glycobiology 5(8): 813-822).

All antibodies contain carbohydrate at conserved positions in theconstant regions of the heavy chain. Each antibody isotype has adistinct variety of N-linked carbohydrate structures. Aside from thecarbohydrate attached to the heavy chain, up to 30% of human IgGs have aglycosylated Fab region. IgG has a single N-linked biantennarycarbohydrate at Asn297 of the CH2 domain. For IgG from either serum orproduced ex vivo in hybridomas or engineered cells, the IgG areheterogeneous with respect to the Asn297 linked carbohydrate (Jefferiset al., 1998, Immunol. Rev. 163:59-76; Wright et al., 1997, TrendsBiotech 15:26-32). For human IgG, the core oligosaccharide normallyconsists of GlcNAc₂Man₃GlcNAc, with differing numbers of outer residues.

The carbohydrate moieties of immunoglobulins disclosed herein will bedescribed with reference to commonly used nomenclature for thedescription of oligosaccharides. A review of carbohydrate chemistrywhich uses this nomenclature is found in Hubbard et al. 1981, Ann. Rev.Biochem. 50:555-583. This nomenclature includes, for instance, Man,which represents mannose; GlcNAc, which represents2-N-acetylglucosamine; Gal which represents galactose; Fuc for fucose;and Glc, which represents glucose. Sialic acids are described by theshorthand notation NeuNAc, for 5-N-acetylneuraminic acid, and NeuNGc for5-glycolylneuraminic.

The term “glycosylation” means the attachment of oligosaccharides(carbohydrates containing two or more simple sugars linked together e.g.from two to about twelve simple sugars linked together) to aglycoprotein. The oligosaccharide side chains are typically linked tothe backbone of the glycoprotein through either N- or O-linkages. Theoligosaccharides of immunoglobulins disclosed herein occur generally areattached to a CH2 domain of an Fc region as N-linked oligosaccharides.“N-linked glycosylation” refers to the attachment of the carbohydratemoiety to an asparagine residue in a glycoprotein chain. The skilledartisan will recognize that, for example, each of murine IgG1, IgG2a,IgG2b and IgG3 as well as human IgG1, IgG2, IgG3, IgG4, IgA and IgD CH2domains have a single site for N-linked glycosylation at amino acidresidue 297 (Kabat et al. Sequences of Proteins of ImmunologicalInterest, 1991).

For the purposes herein, a “mature core carbohydrate structure” refersto a processed core carbohydrate structure attached to an Fc regionwhich generally consists of the following carbohydrate structureGlcNAc(Fucose)-GlcNAc-Man-(Man-GlcNAc)₂ typical of biantennaryoligosaccharides. The mature core carbohydrate structure is attached tothe Fc region of the glycoprotein, generally via N-linkage to Asn297 ofa CH2 domain of the Fc region. A “bisecting GlcNAc” is a GlcNAc residueattached to the β1,4 mannose of the mature core carbohydrate structure.The bisecting GlcNAc can be enzymatically attached to the mature corecarbohydrate structure by a β(1,4)-N-acetylglucosaminyltransferase IIIenzyme (GnTIII). CHO cells do not normally express GnTIII (Stanley etal., 1984, J. Biol. Chem. 261:13370-13378), but may be engineered to doso (Umana et al., 1999, Nature Biotech. 17:176-180).

Described herein are Fc variants that comprise modified glycoforms orengineered glycoforms. By “modified glycoform” or “engineered glycoform”as used herein is meant a carbohydrate composition that is covalentlyattached to a protein, for example an antibody, wherein saidcarbohydrate composition differs chemically from that of a parentprotein. Engineered glycoforms may be useful for a variety of purposes,including but not limited to enhancing or reducing FcγR-mediatedeffector function. In one embodiment, the immunoglobulins disclosedherein are modified to control the level of fucosylated and/or bisectingoligosaccharides that are covalently attached to the Fc region.

A variety of methods are well known in the art for generating modifiedglycoforms (Umaña et al., 1999, Nat Biotechnol 17:176-180; Davies etal., 2001, Biotechnol Bioeng 74:288-294; Shields et al., 2002, J BiolChem 277:26733-26740; Shinkawa et al., 2003, J Biol Chem 278:3466-3473);(U.S. Pat. No. 6,602,684; U.S. Ser. No. 10/277,370; U.S. Ser. No.10/113,929; PCT WO 00/61739A1; PCT WO 01/29246A1; PCT WO 02/31140A1; PCTWO 02/30954A1); (Potelligent™ technology [Biowa, Inc., Princeton, N.J.];GlycoMAb™ glycosylation engineering technology [GLYCART biotechnologyAG, Zurich, Switzerland]; all of which are expressly incorporated byreference). These techniques control the level of fucosylated and/orbisecting oligosaccharides that are covalently attached to the Fcregion, for example by expressing an IgG in various organisms or celllines, engineered or otherwise (for example Lec-13 CHO cells or rathybridoma YB2/0 cells), by regulating enzymes involved in theglycosylation pathway (for example FUT8 [α1,6-fucosyltranserase] and/orβ1-4-N-acetylglucosaminyltransferase III [GnTIII]), or by modifyingcarbohydrate(s) after the IgG has been expressed. Other methods formodifying glycoforms of the immunoglobulins disclosed herein includeusing glycoengineered strains of yeast (Li et al., 2006, NatureBiotechnology 24(2):210-215), moss (Nechansky et al., 2007, Mol Immunjol44(7):1826-8), and plants (Cox et al., 2006, Nat Biotechnol24(12):1591-7). The use of a particular method to generate a modifiedglycoform is not meant to constrain embodiments to that method. Rather,embodiments disclosed herein encompass Fc variants with modifiedglycoforms irrespective of how they are produced.

In one embodiment, immunoglobulins disclosed herein are glycoengineeredto alter the level of sialylation. Higher levels of sialylated Fcglycans in immunoglobulin G molecules can adversely impact functionality(Scallon et al., 2007, Mol Immunol. 44(7):1524-34), and differences inlevels of Fc sialylation can result in modified anti-inflammatoryactivity (Kaneko et al., 2006, Science 313:670-673). Because antibodiesmay acquire anti-inflammatory properties upon sialylation of Fc corepolysaccharide, it may be advantageous to glycoengineer theimmunoglobulins disclosed herein for greater or reduced Fc sialic acidcontent.

Engineered glycoform typically refers to the different carbohydrate oroligosaccharide; thus for example an immuoglobulin may comprise anengineered glycoform. Alternatively, engineered glycoform may refer tothe immunoglobulin that comprises the different carbohydrate oroligosaccharide. In one embodiment, a composition disclosed hereincomprises a glycosylated Fc variant having an Fc region, wherein about51-100% of the glycosylated antibody, e.g., 80-100%, 90-100%, 95-100%,etc. of the antibody in the composition comprises a mature corecarbohydrate structure which lacks fucose. In another embodiment, theantibody in the composition both comprises a mature core carbohydratestructure that lacks fucose and additionally comprises at least oneamino acid modification in the Fc region. In an alternative embodiment,a composition comprises a glycosylated Fc variant having an Fc region,wherein about 51-100% of the glycosylated antibody, 80-100%, or 90-100%,of the antibody in the composition comprises a mature core carbohydratestructure which lacks sialic acid. In another embodiment, the antibodyin the composition both comprises a mature core carbohydrate structurethat lacks sialic acid and additionally comprises at least one aminoacid modification in the Fc region. In yet another embodiment, acomposition comprises a glycosylated Fc variant having an Fc region,wherein about 51-100% of the glycosylated antibody, 80-100%, or 90-100%,of the antibody in the composition comprises a mature core carbohydratestructure which contains sialic acid. In another embodiment, theantibody in the composition both comprises a mature core carbohydratestructure that contains sialic acid and additionally comprises at leastone amino acid modification in the Fc region. In another embodiment, thecombination of engineered glycoform and amino acid modification providesoptimal Fc receptor binding properties to the antibody.

Other Modifications

Immunoglobulins disclosed herein may comprise one or more modificationsthat provide optimized properties that are not specifically related toFcγR- or complement-mediated effector functions per se. Saidmodifications may be amino acid modifications, or may be modificationsthat are made enzymatically or chemically. Such modification(s) likelyprovide some improvement in the immunoglobulin, for example anenhancement in its stability, solubility, function, or clinical use.Disclosed herein are a variety of improvements that may be made bycoupling the immunoglobulins disclosed herein with additionalmodifications.

In one embodiment, the variable region of an antibody disclosed hereinmay be affinity matured, that is to say that amino acid modificationshave been made in the VH and/or VL domains of the antibody to enhancebinding of the antibody to its target antigen. Such types ofmodifications may improve the association and/or the dissociationkinetics for binding to the target antigen. Other modifications includethose that improve selectivity for target antigen vs. alternativetargets. These include modifications that improve selectivity forantigen expressed on target vs. non-target cells. Other improvements tothe target recognition properties may be provided by additionalmodifications. Such properties may include, but are not limited to,specific kinetic properties (i.e. association and dissociationkinetics), selectivity for the particular target versus alternativetargets, and selectivity for a specific form of target versusalternative forms. Examples include full-length versus splice variants,cell-surface vs. soluble forms, selectivity for various polymorphicvariants, or selectivity for specific conformational forms of the targetantigen. Immunoglobulins disclosed herein may comprise one or moremodifications that provide reduced or enhanced internalization of animmunoglobulin.

In one embodiment, modifications are made to improve biophysicalproperties of the immunoglobulins disclosed herein, including but notlimited to stability, solubility, and oligomeric state. Modificationscan include, for example, substitutions that provide more favorableintramolecular interactions in the immunoglobulin such as to providegreater stability, or substitution of exposed nonpolar amino acids withpolar amino acids for higher solubility. A number of optimization goalsand methods are described in U.S. Ser. No. 10/379,392, incorporatedentirely by reference, that may find use for engineering additionalmodifications to further optimize the immunoglobulins disclosed herein.The immunoglobulins disclosed herein can also be combined withadditional modifications that reduce oligomeric state or size, such thattumor penetration is enhanced, or in vivo clearance rates are increasedas desired.

Other modifications to the immunoglobulins disclosed herein includethose that enable the specific formation or homodimeric orhomomultimeric molecules. Such modifications include but are not limitedto engineered disulfides, as well as chemical modifications oraggregation methods which may provide a mechanism for generatingcovalent homodimeric or homomultimers. For example, methods ofengineering and compositions of such molecules are described in Kan etal., 2001, J. Immunol., 2001, 166: 1320-1326; Stevenson et al., 2002,Recent Results Cancer Res. 159: 104-12; U.S. Pat. No. 5,681,566; Caronet al., 1992, J. Exp. Med. 176:1191-1195, and Shopes, 1992, J. Immunol.148(9):2918-22, all incorporated entirely by reference. Additionalmodifications to the variants disclosed herein include those that enablethe specific formation or heterodimeric, heteromultimeric, bifunctional,and/or multifunctional molecules. Such modifications include, but arenot limited to, one or more amino acid substitutions in the CH3 domain,in which the substitutions reduce homodimer formation and increaseheterodimer formation. For example, methods of engineering andcompositions of such molecules are described in Atwell et al., 1997, J.Mol. Biol. 270(1):26-35, and Carter et al., 2001, J. Immunol. Methods248:7-15, both incorporated entirely by reference. Additionalmodifications include modifications in the hinge and CH3 domains, inwhich the modifications reduce the propensity to form dimers.

In further embodiments, the immunoglobulins disclosed herein comprisemodifications that remove proteolytic degradation sites. These mayinclude, for example, protease sites that reduce production yields, aswell as protease sites that degrade the administered protein in vivo. Inone embodiment, additional modifications are made to remove covalentdegradation sites such as deamidation (i.e. deamidation of glutaminyland asparaginyl residues to the corresponding glutamyl and aspartylresidues), oxidation, and proteolytic degradation sites. Deamidationsites that are particular useful to remove are those that have enhancepropensity for deamidation, including, but not limited to asparaginyland gltuamyl residues followed by glycines (NG and QG motifs,respectively). In such cases, substitution of either residue cansignificantly reduce the tendency for deamidation. Common oxidationsites include methionine and cysteine residues. Other covalentmodifications, that can either be introduced or removed, includehydroxylation of proline and lysine, phosphorylation of hydroxyl groupsof seryl or threonyl residues, methylation of the “-amino groups oflysine, arginine, and histidine side chains (T. E. Creighton, Proteins:Structure and Molecular Properties, W.H. Freeman & Co., San Francisco,pp. 79-86 (1983), incorporated entirely by reference), acetylation ofthe N-terminal amine, and amidation of any C-terminal carboxyl group.Additional modifications also may include but are not limited toposttranslational modifications such as N-linked or O-linkedglycosylation and phosphorylation.

Modifications may include those that improve expression and/orpurification yields from hosts or host cells commonly used forproduction of biologics. These include, but are not limited to variousmammalian cell lines (e.g. CHO), yeast cell lines, bacterial cell lines,and plants. Additional modifications include modifications that removeor reduce the ability of heavy chains to form inter-chain disulfidelinkages. Additional modifications include modifications that remove orreduce the ability of heavy chains to form intra-chain disulfidelinkages.

The immunoglobulins disclosed herein may comprise modifications thatinclude the use of unnatural amino acids incorporated using, forexample, the technologies developed by Schultz and colleagues, includingbut not limited to methods described by Cropp & Shultz, 2004, TrendsGenet. 20(12):625-30, Anderson et al., 2004, Proc. Natl. Acad. Sci.U.S.A. 101(2):7566-71, Zhang et al., 2003, 303(5656):371-3, and Chin etal., 2003, Science 301(5635):964-7, all incorporated entirely byreference. In some embodiments, these modifications enable manipulationof various functional, biophysical, immunological, or manufacturingproperties discussed above. In additional embodiments, thesemodifications enable additional chemical modification for otherpurposes. Other modifications are contemplated herein. For example, theimmunoglobulin may be linked to one of a variety of nonproteinaceouspolymers, e.g., polyethylene glycol (PEG), polypropylene glycol,polyoxyalkylenes, or copolymers of polyethylene glycol and polypropyleneglycol. Additional amino acid modifications may be made to enablespecific or non-specific chemical or posttranslational modification ofthe immunoglobulins. Such modifications, include, but are not limited toPEGylation and glycosylation. Specific substitutions that can beutilized to enable PEGylation include, but are not limited to,introduction of novel cysteine residues or unnatural amino acids suchthat efficient and specific coupling chemistries can be used to attach aPEG or otherwise polymeric moiety. Introduction of specificglycosylation sites can be achieved by introducing novel N-X-T/Ssequences into the immunoglobulins disclosed herein.

Modifications to reduce immunogenicity may include modifications thatreduce binding of processed peptides derived from the parent sequence toMHC proteins. For example, amino acid modifications would be engineeredsuch that there are no or a minimal number of immune epitopes that arepredicted to bind, with high affinity, to any prevalent MHC alleles.Several methods of identifying MHC-binding epitopes in protein sequencesare known in the art and may be used to score epitopes in an antibodydisclosed herein. See for example U.S. Ser. No. 09/903,378, U.S. Ser.No. 10/754,296, U.S. Ser. No. 11/249,692, and references cited therein,all expressly incorporated by reference.

In some embodiments, immunoglobulins disclosed herein may be combinedwith immunoglobulins that alter FcRn binding. Such variants may provideimproved pharmacokinetic properties to the immunoglobulins. Inparticular, variants that increase Fc binding to FcRn include but arenot limited to: 250E, 250Q, 428L, 428F, 250Q/428L (Hinton et al., 2004,J. Biol. Chem. 279(8): 6213-6216, Hinton et al. 2006 Journal ofImmunology 176:346-356, U.S. Ser. No. 11/102,621, PCT/US2003/033037,PCT/US2004/011213, U.S. Ser. No. 10/822,300, U.S. Ser. No. 10/687,118,PCT/US2004/034440, U.S. Ser. No. 10/966,673 all entirely incorporated byreference), 256A, 272A, 286A, 305A, 307A, 311A, 312A, 376A, 378Q, 380A,382A, 434A (Shields et al, Journal of Biological Chemistry, 2001,276(9):6591-6604, U.S. Ser. No. 10/982,470, U.S. Pat. No. 6,737,056,U.S. Ser. No. 11/429,793, U.S. Ser. No. 11/429,786, PCT/US2005/029511,U.S. Ser. No. 11/208,422, all entirely incorporated by reference), 252F,252T, 252Y, 252W, 254T, 256S, 256R, 256Q, 256E, 256D, 256T, 309P, 311S,433R, 433S, 433I, 433P, 433Q, 434H, 434F, 434Y, 252Y/254T/256E,433K/434F/436H, 308T/309P/311 S (Dall Acqua et al. Journal ofImmunology, 2002, 169:5171-5180, U.S. Pat. No. 7,083,784,PCT/US97/03321, U.S. Pat. No. 6,821,505, PCT/US01/48432, U.S. Ser. No.11/397,328, all entirely incorporated by reference), 257C, 257M, 257L,257N, 257Y, 279E, 279Q, 279Y, insertion of Ser after 281, 283F, 284E,306Y, 307V, 308F, 308Y 311V, 385H, 385N, (PCT/US2005/041220, U.S. Ser.No. 11/274,065, U.S. Ser. No. 11/436,266 all entirely incorporated byreference) 204D, 284E, 285E, 286D, and 290E (PCT/US2004/037929 entirelyincorporated by reference).

Covalent modifications of antibodies are included within the scope ofimmunoglobulins disclosed herein, and are generally, but not always,done post-translationally. For example, several types of covalentmodifications of the antibody are introduced into the molecule byreacting specific amino acid residues of the antibody with an organicderivatizing agent that is capable of reacting with selected side chainsor the N- or C-terminal residues.

In some embodiments, the covalent modification of the antibodiesdisclosed herein comprises the addition of one or more labels. The term“labeling group” means any detectable label. In some embodiments, thelabeling group is coupled to the antibody via spacer arms of variouslengths to reduce potential steric hindrance. Various methods forlabeling proteins are known in the art and may be used in generatingimmunoglobulins disclosed herein. In general, labels fall into a varietyof classes, depending on the assay in which they are to be detected: a)isotopic labels, which may be radioactive or heavy isotopes; b) magneticlabels (e.g., magnetic particles); c) redox active moieties; d) opticaldyes; enzymatic groups (e.g. horseradish peroxidase, β-galactosidase,luciferase, alkaline phosphatase); e) biotinylated groups; and f)predetermined polypeptide epitopes recognized by a secondary reporter(e.g., leucine zipper pair sequences, binding sites for secondaryantibodies, metal binding domains, epitope tags, etc.). In someembodiments, the labeling group is coupled to the antibody via spacerarms of various lengths to reduce potential steric hindrance. Variousmethods for labeling proteins are known in the art and may be used ingenerating immunoglobulins disclosed herein. Specific labels includeoptical dyes, including, but not limited to, chromophores, phosphors andfluorophores, with the latter being specific in many instances.Fluorophores can be either “small molecule” fluores, or proteinaceousfluores. By “fluorescent label” is meant any molecule that may bedetected via its inherent fluorescent properties.

Conjugates

In one embodiment, the immunoglobulins disclosed herein are antibody“fusion proteins”, sometimes referred to herein as “antibodyconjugates”. The fusion partner or conjugate partner can beproteinaceous or non-proteinaceous; the latter generally being generatedusing functional groups on the antibody and on the conjugate partner.Conjugate and fusion partners may be any molecule, including smallmolecule chemical compounds and polypeptides. For example, a variety ofantibody conjugates and methods are described in Trail et al., 1999,Curr. Opin. Immunol. 11:584-588, incorporated entirely by reference.Possible conjugate partners include but are not limited to cytokines,cytotoxic agents, toxins, radioisotopes, chemotherapeutic agent,anti-angiogenic agents, a tyrosine kinase inhibitors, and othertherapeutically active agents. In some embodiments, conjugate partnersmay be thought of more as payloads, that is to say that the goal of aconjugate is targeted delivery of the conjugate partner to a targetedcell, for example a cancer cell or immune cell, by the immunoglobulin.Thus, for example, the conjugation of a toxin to an immunoglobulintargets the delivery of said toxin to cells expressing the targetantigen. As will be appreciated by one skilled in the art, in realitythe concepts and definitions of fusion and conjugate are overlapping.The designation of a fusion or conjugate is not meant to constrain it toany particular embodiment disclosed herein. Rather, these terms are usedloosely to convey the broad concept that any immunoglobulin disclosedherein may be linked genetically, chemically, or otherwise, to one ormore polypeptides or molecules to provide some desirable property.

Suitable conjugates include, but are not limited to, labels as describedbelow, drugs and cytotoxic agents including, but not limited to,cytotoxic drugs (e.g., chemotherapeutic agents) or toxins or activefragments of such toxins. Suitable toxins and their correspondingfragments include diptheria A chain, exotoxin A chain, ricin A chain,abrin A chain, curcin, crotin, phenomycin, enomycin and the like.Cytotoxic agents also include radiochemicals made by conjugatingradioisotopes to antibodies, or binding of a radionuclide to a chelatingagent that has been covalently attached to the antibody. Additionalembodiments utilize calicheamicin, auristatins, geldanamycin,maytansine, and duocarmycins and analogs; for the latter, see U.S.2003/0050331, incorporated entirely by reference.

In one embodiment, the immunoglobulins disclosed herein are fused orconjugated to a cytokine. By “cytokine” as used herein is meant ageneric term for proteins released by one cell population that act onanother cell as intercellular mediators. For example, as described inPenichet et al., 2001, J. Immunol. Methods 248:91-101, incorporatedentirely by reference, cytokines may be fused to antibody to provide anarray of desirable properties. Examples of such cytokines arelymphokines, monokines, and traditional polypeptide hormones. Includedamong the cytokines are growth hormone such as human growth hormone,N-methionyl human growth hormone, and bovine growth hormone; parathyroidhormone; thyroxine; insulin; proinsulin; relaxin; prorelaxin;glycoprotein hormones such as follicle stimulating hormone (FSH),thyroid stimulating hormone (TSH), and luteinizing hormone (LH); hepaticgrowth factor; fibroblast growth factor; prolactin; placental lactogen;tumor necrosis factor-alpha and -beta; mullerian-inhibiting substance;mouse gonadotropin-associated peptide; inhibin; activin; vascularendothelial growth factor; integrin; thrombopoietin (TPO); nerve growthfactors such as NGF-beta; platelet-growth factor; transforming growthfactors (TGFs) such as TGF-alpha and TGF-beta; insulin-like growthfactor-I and -II; erythropoietin (EPO); osteoinductive factors;interferons such as interferon-alpha, beta, and -gamma; colonystimulating factors (CSFs) such as macrophage-CSF (M-CSF);granulocyte-macrophage-CSF (GM-CSF); and granulocyte-CSF (G-CSF);interleukins (ILs) such as IL-1, IL-1alpha, IL-2, IL-3, IL-4, IL-5,IL-6, IL-7, IL-8, IL-9, IL-10, IL-11, IL-12; IL-15, a tumor necrosisfactor such as TNF-alpha or TNF-beta; C5a; and other polypeptide factorsincluding LIF and kit ligand (KL). As used herein, the term cytokineincludes proteins from natural sources or from recombinant cell culture,and biologically active equivalents of the native sequence cytokines.

In an alternate embodiment, the immunoglobulins disclosed herein arefused, conjugated, or operably linked to a toxin, including but notlimited to small molecule toxins and enzymatically active toxins ofbacterial, fungal, plant or animal origin, including fragments and/orvariants thereof. For example, a variety of immunotoxins and immunotoxinmethods are described in Thrush et al., 1996, Ann. Rev. Immunol.14:49-71, incorporated entirely by reference. Small molecule toxinsinclude but are not limited to calicheamicin, maytansine (U.S. Pat. No.5,208,020, incorporated entirely by reference), trichothene, and CC1065.In one embodiment, an immunoglobulin disclosed herein may be conjugatedto one or more maytansine molecules (e.g. about 1 to about 10 maytansinemolecules per antibody molecule). Maytansine may, for example, beconverted to May-SS-Me which may be reduced to May-SH3 and reacted withmodified antibody (Chari et al., 1992, Cancer Research 52: 127-131,incorporated entirely by reference) to generate a maytansinoid-antibodyconjugate. Another conjugate of interest comprises an immunoglobulinconjugated to one or more calicheamicin molecules. The calicheamicinfamily of antibiotics are capable of producing double-stranded DNAbreaks at sub-picomolar concentrations. Structural analogues ofcalicheamicin that may be used include but are not limited to γ₁ ¹, α₂¹, α₃, N-acetyl-γ₁ ¹, PSAG, and ⊖¹ ₁, (Hinman et al., 1993, CancerResearch 53:3336-3342; Lode et al., 1998, Cancer Research 58:2925-2928)(U.S. Pat. No. 5,714,586; U.S. Pat. No. 5,712,374; U.S. Pat. No.5,264,586; U.S. Pat. No. 5,773,001, all incorporated entirely byreference). Dolastatin 10 analogs such as auristatin E (AE) andmonomethylauristatin E (MMAE) may find use as conjugates for theimmunoglobulins disclosed herein (Doronina et al., 2003, Nat Biotechnol21(7):778-84; Francisco et al., 2003 Blood 102(4):1458-65, bothincorporated entirely by reference). Useful enyzmatically active toxinsinclude but are not limited to diphtheria A chain, nonbinding activefragments of diphtheria toxin, exotoxin A chain (from Pseudomonasaeruginosa), ricin A chain, abrin A chain, modeccin A chain,alpha-sarcin, Aleurites fordii proteins, dianthin proteins, Phytolacaamericana proteins (PAPI, PAPII, and PAP-S), momordica charantiainhibitor, curcin, crotin, sapaonaria officinalis inhibitor, gelonin,mitogellin, restrictocin, phenomycin, enomycin and the tricothecenes.See, for example, PCT WO 93/21232, incorporated entirely by reference.Embodiments further encompass a conjugate between an immunoglobulindisclosed herein and a compound with nucleolytic activity, for example aribonuclease or DNA endonuclease such as a deoxyribonuclease (DNase).

In an alternate embodiment, an immunoglobulin disclosed herein may befused, conjugated, or operably linked to a radioisotope to form aradioconjugate. A variety of radioactive isotopes are available for theproduction of radioconjugate antibodies. Examples include, but are notlimited to, At211, I131, I125, Y90, Re186, Re188, Sm153, Bi212, P32, andradioactive isotopes of Lu. See for example, reference.

In yet another embodiment, an immunoglobulin disclosed herein may beconjugated to a “receptor” (such streptavidin) for utilization in tumorpretargeting wherein the immunoglobulin-receptor conjugate isadministered to the patient, followed by removal of unbound conjugatefrom the circulation using a clearing agent and then administration of a“ligand” (e.g. avidin) which is conjugated to a cytotoxic agent (e.g. aradionucleotide). In an alternate embodiment, the immunoglobulin isconjugated or operably linked to an enzyme in order to employ AntibodyDependent Enzyme Mediated Prodrug Therapy (ADEPT). ADEPT may be used byconjugating or operably linking the immunoglobulin to aprodrug-activating enzyme that converts a prodrug (e.g. a peptidylchemotherapeutic agent, see PCT WO 81/01145, incorporated entirely byreference) to an active anti-cancer drug. See, for example, PCT WO88/07378 and U.S. Pat. No. 4,975,278, both incorporated entirely byreference. The enzyme component of the immunoconjugate useful for ADEPTincludes any enzyme capable of acting on a prodrug in such a way so asto covert it into its more active, cytotoxic form. Enzymes that areuseful in the method disclosed herein include but are not limited toalkaline phosphatase useful for converting phosphate-containing prodrugsinto free drugs; arylsulfatase useful for converting sulfate-containingprodrugs into free drugs; cytosine deaminase useful for convertingnon-toxic 5-fluorocytosine into the anti-cancer drug, 5-fluorouracil;proteases, such as serratia protease, thermolysin, subtilisin,carboxypeptidases and cathepsins (such as cathepsins B and L), that areuseful for converting peptide-containing prodrugs into free drugs;D-alanylcarboxypeptidases, useful for converting prodrugs that containD-amino acid substituents; carbohydrate-cleaving enzymes such as.beta.-galactosidase and neuramimidase useful for convertingglycosylated prodrugs into free drugs; beta-lactamase useful forconverting drugs derivatized with .alpha.-lactams into free drugs; andpenicillin amidases, such as penicillin V amidase or penicillin Gamidase, useful for converting drugs derivatized at their aminenitrogens with phenoxyacetyl or phenylacetyl groups, respectively, intofree drugs. Alternatively, antibodies with enzymatic activity, alsoknown in the art as “abzymes”, can be used to convert the prodrugsdisclosed herein into free active drugs (see, for example, Massey, 1987,Nature 328: 457-458, incorporated entirely by reference).immunoglobulin-abzyme conjugates can be prepared for delivery of theabzyme to a tumor cell population. A variety of additional conjugatesare contemplated for the immunoglobulins disclosed herein. A variety ofchemotherapeutic agents, anti-angiogenic agents, tyrosine kinaseinhibitors, and other therapeutic agents are described below, which mayfind use as immunoglobulin conjugates.

Conjugate partners may be linked to any region of an immunoglobulindisclosed herein, including at the N- or C-termini, or at some residuein-between the termini. A variety of linkers may find use inimmunoglobulins disclosed herein to covalently link conjugate partnersto an immunoglobulin. By “linker”, “linker sequence”, “spacer”,“tethering sequence” or grammatical equivalents thereof, herein is meanta molecule or group of molecules (such as a monomer or polymer) thatconnects two molecules and often serves to place the two molecules inone configuration. Linkers are known in the art; for example, homo- orhetero-bifunctional linkers as are well known (see, 1994 Pierce ChemicalCompany catalog, technical section on cross-linkers, pages 155-200,incorporated entirely by reference). A number of strategies may be usedto covalently link molecules together. These include, but are notlimited to polypeptide linkages between N- and C-termini of proteins orprotein domains, linkage via disulfide bonds, and linkage via chemicalcross-linking reagents. In one aspect of this embodiment, the linker isa peptide bond, generated by recombinant techniques or peptidesynthesis. The linker peptide may predominantly include the followingamino acid residues: Gly, Ser, Ala, or Thr. The linker peptide shouldhave a length that is adequate to link two molecules in such a way thatthey assume the correct conformation relative to one another so thatthey retain the desired activity. Suitable lengths for this purposeinclude at least one and not more than 50 amino acid residues. In oneembodiment, the linker is from about 1 to 30 amino acids in length,e.g., a linker may be 1 to 20 amino acids in length. Useful linkersinclude glycine-serine polymers (including, for example, (GS)n, (GSGGS)n(Set forth as SEQ ID NO:1), (GGGGS)n (Set forth as SEQ ID NO:2) and(GGGS)n (Set forth as SEQ ID NO:3), where n is an integer of at leastone), glycine-alanine polymers, alanine-serine polymers, and otherflexible linkers, as will be appreciated by those in the art.Alternatively, a variety of nonproteinaceous polymers, including but notlimited to polyethylene glycol (PEG), polypropylene glycol,polyoxyalkylenes, or copolymers of polyethylene glycol and polypropyleneglycol, may find use as linkers.

Production of Immunoglobulins

Also disclosed herein are methods for producing and experimentallytesting immunoglobulins. The disclosed methods are not meant toconstrain embodiments to any particular application or theory ofoperation. Rather, the provided methods are meant to illustrategenerally that one or more immunoglobulins may be produced andexperimentally tested to obtain immunoglobulins. General methods forantibody molecular biology, expression, purification, and screening aredescribed in Antibody Engineering, edited by Duebel & Kontermann,Springer-Verlag, Heidelberg, 2001; and Hayhurst & Georgiou, 2001, CurrOpin Chem Biol 5:683-689; Maynard & Georgiou, 2000, Annu Rev Biomed Eng2:339-76; Antibodies: A Laboratory Manual by Harlow & Lane, New York:Cold Spring Harbor Laboratory Press, 1988, all incorporated entirely byreference.

In one embodiment disclosed herein, nucleic acids are created thatencode the immunoglobulins, and that may then be cloned into host cells,expressed and assayed, if desired. Thus, nucleic acids, and particularlyDNA, may be made that encode each protein sequence. These practices arecarried out using well-known procedures. For example, a variety ofmethods that may find use in generating immunoglobulins disclosed hereinare described in Molecular Cloning—A Laboratory Manual, 3^(rd) Ed.(Maniatis, Cold Spring Harbor Laboratory Press, New York, 2001), andCurrent Protocols in Molecular Biology (John Wiley & Sons), bothincorporated entirely by reference. As will be appreciated by thoseskilled in the art, the generation of exact sequences for a librarycomprising a large number of sequences is potentially expensive and timeconsuming. By “library” herein is meant a set of variants in any form,including but not limited to a list of nucleic acid or amino acidsequences, a list of nucleic acid or amino acid substitutions atvariable positions, a physical library comprising nucleic acids thatencode the library sequences, or a physical library comprising thevariant proteins, either in purified or unpurified form. Accordingly,there are a variety of techniques that may be used to efficientlygenerate libraries disclosed herein. Such methods that may find use forgenerating immunoglobulins disclosed herein are described or referencedin U.S. Pat. No. 6,403,312; U.S. Ser. No. 09/782,004; U.S. Ser. No.09/927,790; U.S. Ser. No. 10/218,102; PCT WO 01/40091; and PCT WO02/25588, all incorporated entirely by reference. Such methods includebut are not limited to gene assembly methods, PCR-based method andmethods which use variations of PCR, ligase chain reaction-basedmethods, pooled oligo methods such as those used in synthetic shuffling,error-prone amplification methods and methods which use oligos withrandom mutations, classical site-directed mutagenesis methods, cassettemutagenesis, and other amplification and gene synthesis methods. As isknown in the art, there are a variety of commercially available kits andmethods for gene assembly, mutagenesis, vector subcloning, and the like,and such commercial products find use in for generating nucleic acidsthat encode immunoglobulins.

The immunoglobulins disclosed herein may be produced by culturing a hostcell transformed with nucleic acid, e.g., an expression vector,containing nucleic acid encoding the immunoglobulins, under theappropriate conditions to induce or cause expression of the protein. Theconditions appropriate for expression will vary with the choice of theexpression vector and the host cell, and will be easily ascertained byone skilled in the art through routine experimentation. A wide varietyof appropriate host cells may be used, including but not limited tomammalian cells, bacteria, insect cells, and yeast. For example, avariety of cell lines that may find use in generating immunoglobulinsdisclosed herein are described in the ATCC® cell line catalog, availablefrom the American Type Culture Collection.

In one embodiment, the immunoglobulins are expressed in mammalianexpression systems, including systems in which the expression constructsare introduced into the mammalian cells using virus such as retrovirusor adenovirus. Any mammalian cells may be used, e.g., human, mouse, rat,hamster, and primate cells. Suitable cells also include known researchcells, including but not limited to Jurkat T cells, NIH3T3, CHO, BHK,COS, HEK293, PER C.6, HeLa, Sp2/0, NS0 cells and variants thereof. In analternate embodiment, library proteins are expressed in bacterial cells.Bacterial expression systems are well known in the art, and includeEscherichia coli (E. coli), Bacillus subtilis, Streptococcus cremoris,and Streptococcus lividans. In alternate embodiments, immunoglobulinsare produced in insect cells (e.g. Sf21/Sf9, Trichoplusia niBti-Tn5b1-4) or yeast cells (e.g. S. cerevisiae, Pichia, etc). In analternate embodiment, immunoglobulins are expressed in vitro using cellfree translation systems. In vitro translation systems derived from bothprokaryotic (e.g. E. coli) and eukaryotic (e.g. wheat germ, rabbitreticulocytes) cells are available and may be chosen based on theexpression levels and functional properties of the protein of interest.For example, as appreciated by those skilled in the art, in vitrotranslation is required for some display technologies, for exampleribosome display. In addition, the immunoglobulins may be produced bychemical synthesis methods. Also transgenic expression systems bothanimal (e.g. cow, sheep or goat milk, embryonated hen's eggs, wholeinsect larvae, etc.) and plant (e.g. corn, tobacco, duckweed, etc.)

The nucleic acids that encode the immunoglobulins disclosed herein maybe incorporated into an expression vector in order to express theprotein. A variety of expression vectors may be utilized for proteinexpression. Expression vectors may comprise self-replicatingextra-chromosomal vectors or vectors which integrate into a host genome.Expression vectors are constructed to be compatible with the host celltype. Thus expression vectors which find use in generatingimmunoglobulins disclosed herein include but are not limited to thosewhich enable protein expression in mammalian cells, bacteria, insectcells, yeast, and in in vitro systems. As is known in the art, a varietyof expression vectors are available, commercially or otherwise, that mayfind use for expressing immunoglobulins disclosed herein.

Expression vectors typically comprise a protein operably linked withcontrol or regulatory sequences, selectable markers, any fusionpartners, and/or additional elements. By “operably linked” herein ismeant that the nucleic acid is placed into a functional relationshipwith another nucleic acid sequence. Generally, these expression vectorsinclude transcriptional and translational regulatory nucleic acidoperably linked to the nucleic acid encoding the immunoglobulin, and aretypically appropriate to the host cell used to express the protein. Ingeneral, the transcriptional and translational regulatory sequences mayinclude promoter sequences, ribosomal binding sites, transcriptionalstart and stop sequences, translational start and stop sequences, andenhancer or activator sequences. As is also known in the art, expressionvectors typically contain a selection gene or marker to allow theselection of transformed host cells containing the expression vector.Selection genes are well known in the art and will vary with the hostcell used.

Immunoglobulins may be operably linked to a fusion partner to enabletargeting of the expressed protein, purification, screening, display,and the like. Fusion partners may be linked to the immunoglobulinsequence via a linker sequences. The linker sequence will generallycomprise a small number of amino acids, typically less than ten,although longer linkers may also be used. Typically, linker sequencesare selected to be flexible and resistant to degradation. As will beappreciated by those skilled in the art, any of a wide variety ofsequences may be used as linkers. For example, a common linker sequencecomprises the amino acid sequence GGGGS. A fusion partner may be atargeting or signal sequence that directs immunoglobulin and anyassociated fusion partners to a desired cellular location or to theextracellular media. As is known in the art, certain signaling sequencesmay target a protein to be either secreted into the growth media, orinto the periplasmic space, located between the inner and outer membraneof the cell. A fusion partner may also be a sequence that encodes apeptide or protein that enables purification and/or screening. Suchfusion partners include but are not limited to polyhistidine tags(His-tags) (for example H₆ and H₁₀ or other tags for use withImmobilized Metal Affinity Chromatography (IMAC) systems (e.g. Ni⁺²affinity columns)), GST fusions, MBP fusions, Strep-tag, the BSPbiotinylation target sequence of the bacterial enzyme BirA, and epitopetags which are targeted by antibodies (for example c-myc tags,flag-tags, and the like). As will be appreciated by those skilled in theart, such tags may be useful for purification, for screening, or both.For example, an immunoglobulin may be purified using a His-tag byimmobilizing it to a Ni⁺² affinity column, and then after purificationthe same His-tag may be used to immobilize the antibody to a Ni⁺² coatedplate to perform an ELISA or other binding assay (as described below). Afusion partner may enable the use of a selection method to screenimmunoglobulins (see below). Fusion partners that enable a variety ofselection methods are well-known in the art. For example, by fusing themembers of an immunoglobulin library to the gene III protein, phagedisplay can be employed (Kay et al., Phage display of peptides andproteins: a laboratory manual, Academic Press, San Diego, Calif., 1996;Lowman et al., 1991, Biochemistry 30:10832-10838; Smith, 1985, Science228:1315-1317, incorporated entirely by reference). Fusion partners mayenable immunoglobulins to be labeled. Alternatively, a fusion partnermay bind to a specific sequence on the expression vector, enabling thefusion partner and associated immunoglobulin to be linked covalently ornoncovalently with the nucleic acid that encodes them. The methods ofintroducing exogenous nucleic acid into host cells are well known in theart, and will vary with the host cell used. Techniques include but arenot limited to dextran-mediated transfection, calcium phosphateprecipitation, calcium chloride treatment, polybrene mediatedtransfection, protoplast fusion, electroporation, viral or phageinfection, encapsulation of the polynucleotide(s) in liposomes, anddirect microinjection of the DNA into nuclei. In the case of mammaliancells, transfection may be either transient or stable.

In one embodiment, immunoglobulins are purified or isolated afterexpression. Proteins may be isolated or purified in a variety of waysknown to those skilled in the art. Standard purification methods includechromatographic techniques, including ion exchange, hydrophobicinteraction, affinity, sizing or gel filtration, and reversed-phase,carried out at atmospheric pressure or at high pressure using systemssuch as FPLC and HPLC. Purification methods also includeelectrophoretic, immunological, precipitation, dialysis, andchromatofocusing techniques. Ultrafiltration and diafiltrationtechniques, in conjunction with protein concentration, are also useful.As is well known in the art, a variety of natural proteins bind Fc andantibodies, and these proteins can find use for purification ofimmunoglobulins disclosed herein. For example, the bacterial proteins Aand G bind to the Fc region. Likewise, the bacterial protein L binds tothe Fab region of some antibodies, as of course does the antibody'starget antigen. Purification can often be enabled by a particular fusionpartner. For example, immunoglobulins may be purified using glutathioneresin if a GST fusion is employed, Ni⁺² affinity chromatography if aHis-tag is employed, or immobilized anti-flag antibody if a flag-tag isused. For general guidance in suitable purification techniques, see,e.g. incorporated entirely by reference Protein Purification: Principlesand Practice, 3^(rd) Ed., Scopes, Springer-Verlag, N.Y., 1994,incorporated entirely by reference. The degree of purification necessarywill vary depending on the screen or use of the immunoglobulins. In someinstances no purification is necessary. For example in one embodiment,if the immunoglobulins are secreted, screening may take place directlyfrom the media. As is well known in the art, some methods of selectiondo not involve purification of proteins. Thus, for example, if a libraryof immunoglobulins is made into a phage display library, proteinpurification may not be performed.

In Vitro Experimentation

Immunoglobulins may be screened using a variety of methods, includingbut not limited to those that use in vitro assays, in vivo andcell-based assays, and selection technologies. Automation andhigh-throughput screening technologies may be utilized in the screeningprocedures. Screening may employ the use of a fusion partner or label.The use of fusion partners has been discussed above. By “labeled” hereinis meant that the immunoglobulins disclosed herein have one or moreelements, isotopes, or chemical compounds attached to enable thedetection in a screen. In general, labels fall into three classes: a)immune labels, which may be an epitope incorporated as a fusion partnerthat is recognized by an antibody, b) isotopic labels, which may beradioactive or heavy isotopes, and c) small molecule labels, which mayinclude fluorescent and colorimetric dyes, or molecules such as biotinthat enable other labeling methods. Labels may be incorporated into thecompound at any position and may be incorporated in vitro or in vivoduring protein expression.

In one embodiment, the functional and/or biophysical properties ofimmunoglobulins are screened in an in vitro assay. In vitro assays mayallow a broad dynamic range for screening properties of interest.Properties of immunoglobulins that may be screened include but are notlimited to stability, solubility, and affinity for Fc ligands, forexample FcγRs. Multiple properties may be screened simultaneously orindividually. Proteins may be purified or unpurified, depending on therequirements of the assay. In one embodiment, the screen is aqualitative or quantitative binding assay for binding of immunoglobulinsto a protein or nonprotein molecule that is known or thought to bind theimmunoglobulin. In one embodiment, the screen is a binding assay formeasuring binding to the target antigen. In an alternate embodiment, thescreen is an assay for binding of immunoglobulins to an Fc ligand,including but are not limited to the family of FcγRs, the neonatalreceptor FcRn, the complement protein C1q, and the bacterial proteins Aand G. Said Fc ligands may be from any organism. In one embodiment, Fcligands are from humans, mice, rats, rabbits, and/or monkeys. Bindingassays can be carried out using a variety of methods known in the art,including but not limited to FRET (Fluorescence Resonance EnergyTransfer) and BRET (Bioluminescence Resonance Energy Transfer)-basedassays, AlphaScreen™ (Amplified Luminescent Proximity HomogeneousAssay), Scintillation Proximity Assay, ELISA (Enzyme-LinkedImmunosorbent Assay), SPR (Surface Plasmon Resonance, also known asBIACORE®), isothermal titration calorimetry, differential scanningcalorimetry, gel electrophoresis, and chromatography including gelfiltration. These and other methods may take advantage of some fusionpartner or label of the immunoglobulin. Assays may employ a variety ofdetection methods including but not limited to chromogenic, fluorescent,luminescent, or isotopic labels.

The biophysical properties of immunoglobulins, for example stability andsolubility, may be screened using a variety of methods known in the art.Protein stability may be determined by measuring the thermodynamicequilibrium between folded and unfolded states. For example,immunoglobulins disclosed herein may be unfolded using chemicaldenaturant, heat, or pH, and this transition may be monitored usingmethods including but not limited to circular dichroism spectroscopy,fluorescence spectroscopy, absorbance spectroscopy, NMR spectroscopy,calorimetry, and proteolysis. As will be appreciated by those skilled inthe art, the kinetic parameters of the folding and unfolding transitionsmay also be monitored using these and other techniques. The solubilityand overall structural integrity of an immunoglobulin may bequantitatively or qualitatively determined using a wide range of methodsthat are known in the art. Methods which may find use for characterizingthe biophysical properties of immunoglobulins disclosed herein includegel electrophoresis, isoelectric focusing, capillary electrophoresis,chromatography such as size exclusion chromatography, ion-exchangechromatography, and reversed-phase high performance liquidchromatography, peptide mapping, oligosaccharide mapping, massspectrometry, ultraviolet absorbance spectroscopy, fluorescencespectroscopy, circular dichroism spectroscopy, isothermal titrationcalorimetry, differential scanning calorimetry, analyticalultra-centrifugation, dynamic light scattering, proteolysis, andcross-linking, turbidity measurement, filter retardation assays,immunological assays, fluorescent dye binding assays, protein-stainingassays, microscopy, and detection of aggregates via ELISA or otherbinding assay. Structural analysis employing X-ray crystallographictechniques and NMR spectroscopy may also find use. In one embodiment,stability and/or solubility may be measured by determining the amount ofprotein solution after some defined period of time. In this assay, theprotein may or may not be exposed to some extreme condition, for exampleelevated temperature, low pH, or the presence of denaturant. Becausefunction typically requires a stable, soluble, and/orwell-folded/structured protein, the aforementioned functional andbinding assays also provide ways to perform such a measurement. Forexample, a solution comprising an immunoglobulin could be assayed forits ability to bind target antigen, then exposed to elevated temperaturefor one or more defined periods of time, then assayed for antigenbinding again. Because unfolded and aggregated protein is not expectedto be capable of binding antigen, the amount of activity remainingprovides a measure of the immunoglobulin's stability and solubility.

In one embodiment, the library is screened using one or more cell-basedor in vitro assays. For such assays, immunoglobulins, purified orunpurified, are typically added exogenously such that cells are exposedto individual variants or groups of variants belonging to a library.These assays are typically, but not always, based on the biology of theability of the immunoglobulin to bind to the target antigen and mediatesome biochemical event, for example effector functions like cellularlysis, phagocytosis, ligand/receptor binding inhibition, inhibition ofgrowth and/or proliferation, apoptosis and the like. Such assays ofteninvolve monitoring the response of cells to immunoglobulin, for examplecell survival, cell death, cellular phagocytosis, cell lysis, change incellular morphology, or transcriptional activation such as cellularexpression of a natural gene or reporter gene. For example, such assaysmay measure the ability of immunoglobulins to elicit ADCC, ADCP, or CDC.For some assays additional cells or components, that is in addition tothe target cells, may need to be added, for example serum complement, oreffector cells such as peripheral blood monocytes (PBMCs), NK cells,macrophages, and the like. Such additional cells may be from anyorganism, e.g., humans, mice, rat, rabbit, and monkey. Crosslinked ormonomeric antibodies may cause apoptosis of certain cell linesexpressing the antibody's target antigen, or they may mediate attack ontarget cells by immune cells which have been added to the assay. Methodsfor monitoring cell death or viability are known in the art, and includethe use of dyes, fluorophores, immunochemical, cytochemical, andradioactive reagents. For example, caspase assays orannexin-flourconjugates may enable apoptosis to be measured, and uptakeor release of radioactive substrates (e.g. Chromium-51 release assays)or the metabolic reduction of fluorescent dyes such as alamar blue mayenable cell growth, proliferation or activation to be monitored. In oneembodiment, the DELFIA® EuTDA-based cytotoxicity assay (Perkin Elmer,Mass.) is used. Alternatively, dead or damaged target cells may bemonitored by measuring the release of one or more natural intracellularproteins, for example lactate dehydrogenase. Transcriptional activationmay also serve as a method for assaying function in cell-based assays.In this case, response may be monitored by assaying for natural genes orproteins which may be upregulated or down-regulated, for example therelease of certain interleukins may be measured, or alternativelyreadout may be via a luciferase or GFP-reporter construct. Cell-basedassays may also involve the measure of morphological changes of cells asa response to the presence of an immunoglobulin. Cell types for suchassays may be prokaryotic or eukaryotic, and a variety of cell linesthat are known in the art may be employed. Alternatively, cell-basedscreens are performed using cells that have been transformed ortransfected with nucleic acids encoding the immunoglobulins.

In vitro assays include but are not limited to binding assays, ADCC,CDC, cytotoxicity, proliferation, peroxide/ozone release, chemotaxis ofeffector cells, inhibition of such assays by reduced effector functionantibodies; ranges of activities such as >100× improvement or >100×reduction, blends of receptor activation and the assay outcomes that areexpected from such receptor profiles.

In Vivo Experimentation

The biological properties of the immunoglobulins disclosed herein may becharacterized in cell, tissue, and whole organism experiments. As isknown in the art, drugs are often tested in animals, including but notlimited to mice, rats, rabbits, dogs, cats, pigs, and monkeys, in orderto measure a drug's efficacy for treatment against a disease or diseasemodel, or to measure a drug's pharmacokinetics, toxicity, and otherproperties. Said animals may be referred to as disease models. Withrespect to the immunoglobulins disclosed herein, a particular challengearises when using animal models to evaluate the potential for in-humanefficacy of candidate polypeptides—this is due, at least in part, to thefact that immunoglobulins that have a specific effect on the affinityfor a human Fc receptor may not have a similar affinity effect with theorthologous animal receptor. These problems can be further exacerbatedby the inevitable ambiguities associated with correct assignment of trueorthologues (Mechetina et al., Immunogenetics, 2002 54:463-468,incorporated entirely by reference), and the fact that some orthologuessimply do not exist in the animal (e.g. humans possess an FcγRIIawhereas mice do not). Therapeutics are often tested in mice, includingbut not limited to mouse strains NZB, NOD, BXSB, MRL/Ipr, K/BxN andtransgenics (including knockins and knockouts). Such mice can developvarious autoimmune conditions that resemble human organ specific,systemic autoimmune or inflammatory disease pathologies such as systemiclupus erythematosus (SLE) and rheumatoid arthritis (RA). For example, animmunoglobulin disclosed herein intended for autoimmune diseases may betested in such mouse models by treating the mice to determine theability of the immunoglobulin to reduce or inhibit the development ofthe disease pathology. Because of the incompatibility between the mouseand human Fcγ receptor system, an alternative approach is to use amurine SCID model in which immune deficient mice are engrafted withhuman PBLs or PBMCs (huPBL-SCID, huPBMC-SCID) providing asemi-functional human immune system with human effector cells and Fcreceptors. In such a model, an antigen challenge (such as tetanustoxoid) activates the B cells to differentiate into plasma cells andsecrete immunoglobulins, thus reconstituting antigen specific humoralimmunity. Therefore, a dual targeting immunoglobulin disclosed hereinthat specifically binds to an antigen (such as CD19 or CD79a/b) andFcγRIIb on B cells may be tested to examine the ability to specificallyinhibit B cell differentiation. Such experimentation may providemeaningful data for determination of the potential of saidimmunoglobulin to be used as a therapeutic. Other organisms, e.g.,mammals, may also be used for testing. For example, because of theirgenetic similarity to humans, monkeys can be suitable therapeuticmodels, and thus may be used to test the efficacy, toxicity,pharmacokinetics, or other property of the immunoglobulins disclosedherein. Tests of the immunoglobulins disclosed herein in humans areultimately required for approval as drugs, and thus of course theseexperiments are contemplated. Thus the immunoglobulins disclosed hereinmay be tested in humans to determine their therapeutic efficacy,toxicity, pharmacokinetics, and/or other clinical properties.

The immunoglobulins disclosed herein may confer superior performance onFc-containing therapeutics in animal models or in humans. The receptorbinding profiles of such immunoglobulins, as described in thisspecification, may, for example, be selected to increase the potency ofcytotoxic drugs or to target specific effector functions or effectorcells to improve the selectivity of the drug's action. Further, receptorbinding profiles can be selected that may reduce some or all effectorfunctions thereby reducing the side-effects or toxicity of suchFc-containing drug. For example, an immunoglobulin with reduced bindingto FcγRIIIa, FcγRI and FcγRIIa can be selected to eliminate mostcell-mediated effector function, or an immunoglobulin with reducedbinding to C1q may be selected to limit complement-mediated effectorfunctions. In some contexts, such effector functions are known to havepotential toxic effects. Therefore eliminating them may increase thesafety of the Fc-bearing drug and such improved safety may becharacterized in animal models. In some contexts, such effectorfunctions are known to mediate the desirable therapeutic activity.Therefore enhancing them may increase the activity or potency of theFc-bearing drug and such improved activity or potency may becharacterized in animal models.

In some embodiments, immunoglobulins disclosed herein may be assessedfor efficacy in clinically relevant animal models of various humandiseases. In many cases, relevant models include various transgenicanimals for specific antigens and receptors.

Relevant transgenic models such as those that express human Fc receptors(e.g., CD32b) could be used to evaluate and test immunoglobulins andFc-fusions in their efficacy. The evaluation of immunoglobulins by theintroduction of human genes that directly or indirectly mediate effectorfunction in mice or other rodents may enable physiological studies ofefficacy in autoimmune disorders and RA. Human Fc receptors such asFcγRIIb may possess polymorphisms such as that in gene promoter (−343from G to C) or transmembrane domain of the receptor 187 I or T whichwould further enable the introduction of specific and combinations ofhuman polymorphisms into rodents. The various studies involvingpolymorphism-specific FcRs is not limited to this section, howeverencompasses all discussions and applications of FcRs in general asspecified in throughout this application. Immunoglobulins disclosedherein may confer superior activity on Fc-containing drugs in suchtransgenic models, in particular variants with binding profilesoptimized for human FcγRIIb mediated activity may show superior activityin transgenic CD32b mice. Similar improvements in efficacy in micetransgenic for the other human Fc receptors, e.g. FcγRIIa, FcγRI, etc.,may be observed for immunoglobulins with binding profiles optimized forthe respective receptors. Mice transgenic for multiple human receptorswould show improved activity for immunoglobulins with binding profilesoptimized for the corresponding multiple receptors.

Because of the difficulties and ambiguities associated with using animalmodels to characterize the potential efficacy of candidate therapeuticantibodies in a human patient, some variant polypeptides disclosedherein may find utility as proxies for assessing potential in-humanefficacy. Such proxy molecules may mimic—in the animal system—the FcRand/or complement biology of a corresponding candidate humanimmunoglobulin. This mimicry is most likely to be manifested by relativeassociation affinities between specific immunoglobulins and animal vs.human receptors. For example, if one were using a mouse model to assessthe potential in-human efficacy of an Fc variant that has reducedaffinity for the inhibitory human FcγRIIb, an appropriate proxy variantwould have reduced affinity for mouse FcγRII. It should also be notedthat the proxy Fc variants could be created in the context of a human Fcvariant, an animal Fc variant, or both.

In one embodiment, the testing of immunoglobulins may include study ofefficacy in primates (e.g. cynomolgus monkey model) to facilitate theevaluation of depletion of specific target cells harboring the targetantigen. Additional primate models include but are not limited to use ofthe rhesus monkey to assess Fc polypeptides in therapeutic studies ofautoimmune, transplantation and cancer.

Toxicity studies are performed to determine antibody or Fc-fusionrelated-effects that cannot be evaluated in standard pharmacologyprofiles, or occur only after repeated administration of the agent. Mosttoxicity tests are performed in two species—a rodent and a non-rodent—toensure that any unexpected adverse effects are not overlooked before newtherapeutic entities are introduced into man. In general, these modelsmay measure a variety of toxicities including genotoxicity, chronictoxicity, immunogenicity, reproductive/developmental toxicity andcarcinogenicity. Included within the aforementioned parameters arestandard measurement of food consumption, bodyweight, antibodyformation, clinical chemistry, and macro- and microscopic examination ofstandard organs/tissues (e.g. cardiotoxicity). Additional parameters ofmeasurement are injection site trauma and the measurement ofneutralizing antibodies, if any. Traditionally, monoclonal antibodytherapeutics, naked or conjugated, are evaluated for cross-reactivitywith normal tissues, immunogenicity/antibody production, conjugate orlinker toxicity and “bystander” toxicity of radiolabelled species.Nonetheless, such studies may have to be individualized to addressspecific concerns and following the guidance set by ICH S6 (Safetystudies for biotechnological products, also noted above). As such, thegeneral principles are that the products are sufficiently wellcharacterized, impurities/contaminants have been removed, that the testmaterial is comparable throughout development, that GLP compliance ismaintained.

The pharmacokinetics (PK) of the immunoglobulins disclosed herein may bestudied in a variety of animal systems, with the most relevant beingnon-human primates such as the cynomolgus and rhesus monkeys. Single orrepeated i.v./s.c. administrations over a dose range of 6000-fold(0.05-300 mg/kg) can be evaluated for half-life (days to weeks) usingplasma concentration and clearance. Volume of distribution at a steadystate and level of systemic absorbance can also be measured. Examples ofsuch parameters of measurement generally include maximum observed plasmaconcentration (Cmax), the time to reach Cmax (Tmax), the area under theplasma concentration-time curve from time 0 to infinity [AUC(0-inf] andapparent elimination half-life (T½). Additional measured parameterscould include compartmental analysis of concentration-time data obtainedfollowing i.v. administration and bioavailability. Examples ofpharmacological/toxicological studies using cynomolgus monkeys have beenestablished for Rituxan and Zevalin in which monoclonal antibodies toCD20 are cross-reactive. Biodistribution, dosimetry (for radiolabelledantibodies), and PK studies can also be done in rodent models. Suchstudies would evaluate tolerance at all doses administered, toxicity tolocal tissues, preferential localization to rodent xenograft animalmodels, and depletion of target cells (e.g. CD20 positive cells).

The immunoglobulins disclosed herein may confer superiorpharmacokinetics on Fc-containing therapeutics in animal systems or inhumans. For example, increased binding to FcRn may increase thehalf-life and exposure of the Fc-containing drug. Alternatively,decreased binding to FcRn may decrease the half-life and exposure of theFc-containing drug in cases where reduced exposure is favorable such aswhen such drug has side-effects.

It is known in the art that the array of Fc receptors is differentiallyexpressed on various immune cell types, as well as in different tissues.Differential tissue distribution of Fc receptors may ultimately have animpact on the pharmacodynamic (PD) and pharmacokinetic (PK) propertiesof immunoglobulins disclosed herein. Because immunoglobulins of thepresentation have varying affinities for the array of Fc receptors,further screening of the polypeptides for PD and/or PK properties may beextremely useful for defining the optimal balance of PD, PK, andtherapeutic efficacy conferred by each candidate polypeptide.

Pharmacodynamic studies may include, but are not limited to, targetingspecific cells or blocking signaling mechanisms, measuring inhibition ofantigen-specific antibodies etc. The immunoglobulins disclosed hereinmay target particular effector cell populations and thereby directFc-containing drugs to induce certain activities to improve potency orto increase penetration into a particularly favorable physiologicalcompartment. For example, neutrophil activity and localization can betargeted by an immunoglobulin that targets FcγRIIIb. Suchpharmacodynamic effects may be demonstrated in animal models or inhumans.

Clinical Use

The immunoglobulins disclosed herein may find use in a wide range ofproducts. In one embodiment an immunoglobulin disclosed herein is atherapeutic, a diagnostic, or a research reagent. The immunoglobulinsmay find use in a composition that is monoclonal or polyclonal. Theimmunoglobulins disclosed herein may be used for therapeutic purposes.As will be appreciated by those in the art, the immunoglobulinsdisclosed herein may be used for any therapeutic purpose thatantibodies, and the like may be used for. The immunoglobulins may beadministered to a patient to treat disorders including but not limitedto autoimmune and inflammatory diseases, infectious diseases, andcancer.

A “patient” for the purposes disclosed herein includes both humans andother animals, e.g., other mammals. Thus the immunoglobulins disclosedherein have both human therapy and veterinary applications. The term“treatment” or “treating” as disclosed herein is meant to includetherapeutic treatment, as well as prophylactic, or suppressive measuresfor a disease or disorder. Thus, for example, successful administrationof an immunoglobulin prior to onset of the disease results in treatmentof the disease. As another example, successful administration of anoptimized immunoglobulin after clinical manifestation of the disease tocombat the symptoms of the disease comprises treatment of the disease.“Treatment” and “treating” also encompasses administration of anoptimized immunoglobulin after the appearance of the disease in order toeradicate the disease. Successful administration of an agent after onsetand after clinical symptoms have developed, with possible abatement ofclinical symptoms and perhaps amelioration of the disease, comprisestreatment of the disease. Those “in need of treatment” include mammalsalready having the disease or disorder, as well as those prone to havingthe disease or disorder, including those in which the disease ordisorder is to be prevented.

In one embodiment, an immunoglobulin disclosed herein is administered toa patient having a disease involving inappropriate expression of aprotein or other molecule. Within the scope disclosed herein this ismeant to include diseases and disorders characterized by aberrantproteins, due for example to alterations in the amount of a proteinpresent, protein localization, posttranslational modification,conformational state, the presence of a mutant or pathogen protein, etc.Similarly, the disease or disorder may be characterized by alterationsmolecules including but not limited to polysaccharides and gangliosides.An overabundance may be due to any cause, including but not limited tooverexpression at the molecular level, prolonged or accumulatedappearance at the site of action, or increased activity of a proteinrelative to normal. Included within this definition are diseases anddisorders characterized by a reduction of a protein. This reduction maybe due to any cause, including but not limited to reduced expression atthe molecular level, shortened or reduced appearance at the site ofaction, mutant forms of a protein, or decreased activity of a proteinrelative to normal. Such an overabundance or reduction of a protein canbe measured relative to normal expression, appearance, or activity of aprotein, and said measurement may play an important role in thedevelopment and/or clinical testing of the immunoglobulins disclosedherein.

By “cancer” and “cancerous” herein refer to or describe thephysiological condition in mammals that is typically characterized byunregulated cell growth. Examples of cancer include but are not limitedto carcinoma, lymphoma, blastoma, sarcoma (including liposarcoma),neuroendocrine tumors, mesothelioma, schwanoma, meningioma,adenocarcinoma, melanoma, and leukemia or lymphoid malignancies.

More particular examples of such cancers include hematologicmalignancies, such as Hodgkin's lymphoma; non-Hodgkin's lymphomas(Burkitt's lymphoma, small lymphocytic lymphoma/chronic lymphocyticleukemia, mycosis fungoides, mantle cell lymphoma, follicular lymphoma,diffuse large B-cell lymphoma, marginal zone lymphoma, hairy cellleukemia and lymphoplasmacytic leukemia), tumors of lymphocyte precursorcells, including B-cell acute lymphoblastic leukemia/lymphoma, andT-cell acute lymphoblastic leukemia/lymphoma, thymoma, tumors of themature T and NK cells, including peripheral T-cell leukemias, adultT-cell leukemia/T-cell lymphomas and large granular lymphocyticleukemia, Langerhans cell histocytosis, myeloid neoplasias such as acutemyelogenous leukemias, including AML with maturation, AML withoutdifferentiation, acute promyelocytic leukemia, acute myelomonocyticleukemia, and acute monocytic leukemias, myelodysplastic syndromes, andchronic myeloproliferative disorders, including chronic myelogenousleukemia; tumors of the central nervous system such as glioma,glioblastoma, neuroblastoma, astrocytoma, medulloblastoma, ependymoma,and retinoblastoma; solid tumors of the head and neck (eg.nasopharyngeal cancer, salivary gland carcinoma, and esophagael cancer),lung (eg. small-cell lung cancer, non-small cell lung cancer,adenocarcinoma of the lung and squamous carcinoma of the lung),digestive system (eg. gastric or stomach cancer includinggastrointestinal cancer, cancer of the bile duct or biliary tract, coloncancer, rectal cancer, colorectal cancer, and anal carcinoma),reproductive system (eg. testicular, penile, or prostate cancer,uterine, vaginal, vulval, cervical, ovarian, and endometrial cancer),skin (eg. melanoma, basal cell carcinoma, squamous cell cancer, actinickeratosis), liver (eg. liver cancer, hepatic carcinoma, hepatocellularcancer, and hepatoma), bone (eg. osteoclastoma, and osteolytic bonecancers) additional tissues and organs (eg. pancreatic cancer, bladdercancer, kidney or renal cancer, thyroid cancer, breast cancer, cancer ofthe peritoneum, and Kaposi's sarcoma), and tumors of the vascular system(eg. angiosarcoma and hemagiopericytoma).

By “autoimmune diseases” herein include allogenic islet graft rejection,alopecia areata, ankylosing spondylitis, antiphospholipid syndrome,autoimmune Addison's disease, antineutrophil cytoplasmic autoantibodies(ANCA), autoimmune diseases of the adrenal gland, autoimmune hemolyticanemia, autoimmune hepatitis, autoimmune myocarditis, autoimmuneneutropenia, autoimmune oophoritis and orchitis, autoimmunethrombocytopenia, autoimmune urticaria, Behcet's disease, bullouspemphigoid, cardiomyopathy, Castleman's syndrome, celiacspruce-dermatitis, chronic fatigue immune disfunction syndrome, chronicinflammatory demyelinating polyneuropathy, Churg-Strauss syndrome,cicatrical pemphigoid, CREST syndrome, cold agglutinin disease, Crohn'sdisease, dermatomyositis, discoid lupus, essential mixedcryoglobulinemia, factor VIII deficiency, fibromyalgia-fibromyositis,glomerulonephritis, Grave's disease, Guillain-Barre, Goodpasture'ssyndrome, graft-versus-host disease (GVHD), Hashimoto's thyroiditis,hemophilia A, idiopathic pulmonary fibrosis, idiopathic thrombocytopeniapurpura (ITP), IgA neuropathy, IgM polyneuropathies, immune mediatedthrombocytopenia, juvenile arthritis, Kawasaki's disease, lichenplantus, lupus erthematosis, Meniere's disease, mixed connective tissuedisease, multiple sclerosis, type 1 diabetes mellitus, myastheniagravis, pemphigus vulgaris, pernicious anemia, polyarteritis nodosa,polychrondritis, polyglandular syndromes, polymyalgia rheumatica,polymyositis and dermatomyositis, primary agammaglobinulinemia, primarybiliary cirrhosis, psoriasis, psoriatic arthritis, Reynauld'sphenomenon, Reiter's syndrome, rheumatoid arthritis, sarcoidosis,scleroderma, Sjorgen's syndrome, solid organ transplant rejection,stiff-man syndrome, systemic lupus erythematosus, takayasu arteritis,temporal arteristis/giant cell arteritis, thrombotic thrombocytopeniapurpura, ulcerative colitis, uveitis, vasculitides such as dermatitisherpetiformis vasculitis, vitiligo, and Wegner's granulomatosis.

By “inflammatory disorders” herein include acute respiratory distresssyndrome (ARDS), acute septic arthritis, adjuvant arthritis (Prakken etal., Springer Semin Immunopathol., 2003 August; 25(1):47-63,incorporated entirely by reference), juvenile idiopathic arthritis (deKleer et al., Arthritis Rheum. 2003 July; 47(7):2001-10, incorporatedentirely by reference), allergic encephalomyelitis, allergic rhinitis,allergic vasculitis, allergy, asthma, atherosclerosis, chronicinflammation due to chronic bacterial or viral infectionis, chronicobstructive pulmonary disease (COPD), coronary artery disease,encephalitis, inflammatory bowel disease, inflammatory osteolysis,inflammation associated with acute and delayed hypersensitivityreactions, inflammation associated with tumors, peripheral nerve injuryor demyelinating diseases, inflammation associated with tissue traumasuch as burns and ischemia, inflammation due to meningitis, multipleorgan injury syndrome, pulmonary fibrosis, sepsis and septic shock,Stevens-Johnson syndrome, undifferentiated arthropy, andundifferentiated spondyloarthropathy.

Some autoimmune and inflammatory diseases that may be targeted by theimmunoglobulins disclosed herein include Systemic Lupus Erythematosus,Rheumatoid arthritis, Sjogren's syndrome, Multiple sclerosis, Idiopathicthrombocytopenic purpura (ITP), Graves disease, Inflammatory boweldisease, Psoriasis, Type I diabetes, and Asthma.

Immunoglobulins disclosed herein may be utilized to modulate theactivity of the immune system, and in some cases to mimic the effects ofIVIg therapy in a more controlled, specific, and efficient manner. Thusimmunoglobulins disclosed herein may be used as immunomodulatorytherapeutics. IVIg is effectively a high dose of immunoglobulinsdelivered intravenously. In general, IVIg has been used to downregulateautoimmune conditions. It has been hypothesized that the therapeuticmechanism of action of IVIg involves ligation of Fc receptors at highfrequency (J. Bayry et al., 2003, Transfusion Clinique et Biologique 10:165-169; Binstadt et al., 2003, J Allergy Clin. Immunol, 697-704).Indeed animal models of (thrombocytopenia purpura (ITP) show that theisolated Fc are the active portion of IVIg (Samuelsson et al, 2001,Pediatric Research 50(5), 551). For use in therapy, immunoglobulin's areharvested from thousands of donors, with all of the concomitant problemsassociated with non-recombinant biotherapeutics collected from humans.An immunoglobulin disclosed herein should serve all of the roles of IVIgwhile being manufactured as a recombinant protein rather than harvestedfrom donors.

The immunomodulatory effects of IVIg may be dependent on productiveinteraction with one or more Fc ligands, including but not limited toFcγRs, complement proteins, and FcRn. In some embodiments,immunoglobulins disclosed herein may be used to promoteanti-inflammatory activity (Samuelsson et al., 2001, Science 291:484-486) and or to reduce autoimmunity (Hogarth, 2002, Current Opinionin Immunology, 14:798-802). In one embodiment, Fc variants that provideenhanced binding to the inhibitory receptor FcγRIIb provide anenhancement to the IVIg therapeutic approach. Such Fc variants wouldthus function as FcγRIIb agonists, and would be expected to enhance thebeneficial effects of IVIg as an autoimmune disease therapeutic and alsoas a modulator of B-cell proliferation. In addition, suchFcγRIIb-enhanced Fc variants may also be further modified to have thesame or limited binding to other receptors. In additional embodiments,the Fc variants with enhanced FcγRIIb affinity may be combined withmutations that reduce or ablate to other receptors, thereby potentiallyfurther minimizing side effects during therapeutic use.

Binding to or blocking Fc receptors on immune system cells may be usedto influence immune response in immunological conditions including butnot limited to idiopathic thrombocytopenia purpura (ITP) and rheumatoidarthritis (RA) among others. By use of the affinity enhanced Fc variantsdisclosed herein, the dosages required in typical IVIg applications maybe reduced while obtaining a substantially similar therapeutic effect.Binding enhancements to FcγRIIb would increase expression or inhibitoryactivity, as needed, of that receptor and improve efficacy. In addition,modulated affinity of the Fc variants for activating FcγRs, FcRn, and/oralso complement may also provide benefits.

Such immunomodulatory applications of the immunoglobulins disclosedherein may also be utilized in the treatment of oncological indications,especially those for which therapy involves antibody-dependant cytotoxicmechanisms. For example, an Fc variant that enhances affinity to FcγRIIbmay be used to antagonize this inhibitory receptor, for example bybinding to the Fc/FcγRIIb binding site but failing to trigger, orreducing cell signaling, potentially enhancing the effect ofantibody-based anti-cancer therapy. Such Fc variants, functioning asFcγRIIb antagonists, may either block the inhibitory properties ofFcγRIIb, or induce its inhibitory function as in the case of IVIg. AnFcγRIIb antagonist may be used as co-therapy in combination with anyother therapeutic, including but not limited to antibodies, acting onthe basis of ADCC related cytotoxicity. FcγRIIb antagonistic Fc variantsof this type may be isolated Fc or Fc fragments, although in alternateembodiments immunoglobulins may be used.

By “infectious diseases” herein include diseases caused by pathogenssuch as viruses, bacteria, fungi, protozoa, and parasites. Infectiousdiseases may be caused by viruses including adenovirus, cytomegalovirus,dengue, Epstein-Barr, hanta, hepatitis A, hepatitis B, hepatitis C,herpes simplex type I, herpes simplex type II, human immunodeficiencyvirus, (HIV), human papilloma virus (HPV), influenza, measles, mumps,papova virus, polio, respiratory syncytial virus, rinderpest,rhinovirus, rotavirus, rubella, SARS virus, smallpox, viral meningitis,and the like. Infections diseases may also be caused by bacteriaincluding Bacillus antracis, Borrelia burgdorferi, Campylobacter jejuni,Chlamydia trachomatis, Clostridium botulinum, Clostridium tetani,Diptheria, E. coli, Legionella, Helicobacter pylori, Mycobacteriumrickettsia, Mycoplasma nesisseria, Pertussis, Pseudomonas aeruginosa, S.pneumonia, Streptococcus, Staphylococcus, Vibria cholerae, Yersiniapestis, and the like. Infectious diseases may also be caused by fungisuch as Aspergillus fumigatus, Blastomyces dermatitidis, Candidaalbicans, Coccidioides immitis, Cryptococcus neoformans, Histoplasmacapsulatum, Penicillium marneffei, and the like. Infectious diseases mayalso be caused by protozoa and parasites such as chlamydia, kokzidioa,leishmania, malaria, rickettsia, trypanosoma, and the like.

Furthermore, antibodies disclosed herein may be used to prevent or treatadditional conditions including but not limited to heart conditions suchas congestive heart failure (CHF), myocarditis and other conditions ofthe myocardium; skin conditions such as rosecea, acne, and eczema; boneand tooth conditions such as bone loss, osteoporosis, Paget's disease,Langerhans' cell histiocytosis, periodontal disease, disuse osteopenia,osteomalacia, monostotic fibrous dysplasia, polyostotic fibrousdysplasia, bone metastasis, bone pain management, humoral malignanthypercalcemia, periodontal reconstruction, spinal cord injury, and bonefractures; metabolic conditions such as Gaucher's disease; endocrineconditions such as Cushing's syndrome; and neurological conditions.

A number of the receptors that may interact with the immunoglobulinsdisclosed herein are polymorphic in the human population. For a givenpatient or population of patients, the efficacy of the immunoglobulinsdisclosed herein may be affected by the presence or absence of specificpolymorphisms in proteins. For example, FcγRIIIa is polymorphic atposition 158, which is commonly either V (high affinity) or F (lowaffinity). Patients with the V/V homozygous genotype are observed tohave a better clinical response to treatment with the anti-CD20 antibodyRituxan® (rituximab), likely because these patients mount a stronger NKresponse (Dall'Ozzo et. al. (2004) Cancer Res. 64:4664-9, incorporatedentirely by reference). Additional polymorphisms include but are notlimited to FcγRIIa R131 or H131, and such polymorphisms are known toeither increase or decrease Fc binding and subsequent biologicalactivity, depending on the polymorphism. immunoglobulins disclosedherein may bind preferentially to a particular polymorphic form of areceptor, for example FcγRIIIa 158 V, or to bind with equivalentaffinity to all of the polymorphisms at a particular position in thereceptor, for example both the 158V and 158F polymorphisms of FcγRIIIa.In one embodiment, immunoglobulins disclosed herein may have equivalentbinding to polymorphisms may be used in an antibody to eliminate thedifferential efficacy seen in patients with different polymorphisms.Such a property may give greater consistency in therapeutic response andreduce non-responding patient populations. Such variant Fc withidentical binding to receptor polymorphisms may have increasedbiological activity, such as ADCC, CDC or circulating half-life, oralternatively decreased activity, via modulation of the binding to therelevant Fc receptors. In one embodiment, immunoglobulins disclosedherein may bind with higher or lower affinity to one of thepolymorphisms of a receptor, either accentuating the existing differencein binding or reversing the difference. Such a property may allowcreation of therapeutics particularly tailored for efficacy with apatient population possessing such polymorphism. For example, a patientpopulation possessing a polymorphism with a higher affinity for aninhibitory receptor such as FcγRIIb could receive a drug containing anFc variant with reduced binding to such polymorphic form of thereceptor, creating a more efficacious drug.

In one embodiment, patients are screened for one or more polymorphismsin order to predict the efficacy of the immunoglobulins disclosedherein. This information may be used, for example, to select patients toinclude or exclude from clinical trials or, post-approval, to provideguidance to physicians and patients regarding appropriate dosages andtreatment options. For example, in patients that are homozygous orheterozygous for FcγRIIIa 158F antibody drugs such as the anti-CD20 mAb,Rituximab are minimally effective (Carton 2002 Blood 99: 754-758; Weng2003 J. Clin. Oncol. 21:3940-3947, both incorporated entirely byreference); such patients may show a much better clinical response tothe antibodies disclosed herein. In one embodiment, patients areselected for inclusion in clinical trials for an immunoglobulindisclosed herein if their genotype indicates that they are likely torespond significantly better to an immunoglobulin disclosed herein ascompared to one or more currently used immunoglobulin therapeutics. Inanother embodiment, appropriate dosages and treatment regimens aredetermined using such genotype information. In another embodiment,patients are selected for inclusion in a clinical trial or for receiptof therapy post-approval based on their polymorphism genotype, wheresuch therapy contains an immunoglobulin engineered to be specificallyefficacious for such population, or alternatively where such therapycontains an Fc variant that does not show differential activity to thedifferent forms of the polymorphism.

Also disclosed are diagnostic tests to identify patients who are likelyto show a favorable clinical response to an immunoglobulin disclosedherein, or who are likely to exhibit a significantly better responsewhen treated with an immunoglobulin disclosed herein versus one or morecurrently used immunoglobulin therapeutics. Any of a number of methodsfor determining FcγR polymorphisms in humans known in the art may beused.

Furthermore, also disclosed are prognostic tests performed on clinicalsamples such as blood and tissue samples. Such tests may assay foreffector function activity, including but not limited to ADCC, CDC,phagocytosis, and opsonization, or for killing, regardless of mechanism,of cancerous or otherwise pathogenic cells. In one embodiment, ADCCassays, such as those described previously, are used to predict, for aspecific patient, the efficacy of a given immunoglobulin disclosedherein. Such information may be used to identify patients for inclusionor exclusion in clinical trials, or to inform decisions regardingappropriate dosages and treatment regemins. Such information may also beused to select a drug that contains a particular immunoglobulin thatshows superior activity in such assay.

Formulation

Pharmaceutical compositions are contemplated wherein an immunoglobulindisclosed herein and one or more therapeutically active agents areformulated. Formulations of the immunoglobulins disclosed herein areprepared for storage by mixing said immunoglobulin having the desireddegree of purity with optional pharmaceutically acceptable carriers,excipients or stabilizers (Remington's Pharmaceutical Sciences 16thedition, Osol, A. Ed., 1980, incorporated entirely by reference), in theform of lyophilized formulations or aqueous solutions. Acceptablecarriers, excipients, or stabilizers are nontoxic to recipients at thedosages and concentrations employed, and include buffers such asphosphate, citrate, acetate, and other organic acids; antioxidantsincluding ascorbic acid and methionine; preservatives (such asoctadecyldimethylbenzyl ammonium chloride; hexamethonium chloride;benzalkonium chloride, benzethonium chloride; phenol, butyl orbenzylalcohol; alkyl parabens such as methyl or propyl paraben; catechol;resorcinol; cyclohexanol; 3-pentanol; and m-cresol); low molecularweight (less than about 10 residues) polypeptides; proteins, such asserum albumin, gelatin, or immunoglobulins; hydrophilic polymers such aspolyvinylpyrrolidone; amino acids such as glycine, glutamine,asparagine, histidine, arginine, or lysine; monosaccharides,disaccharides, and other carbohydrates including glucose, mannose, ordextrins; chelating agents such as EDTA; sugars such as sucrose,mannitol, trehalose or sorbitol; sweeteners and other flavoring agents;fillers such as microcrystalline cellulose, lactose, corn and otherstarches; binding agents; additives; coloring agents; salt-formingcounter-ions such as sodium; metal complexes (e.g. Zn-proteincomplexes); and/or non-ionic surfactants such as TWEEN™, PLURONICS™ orpolyethylene glycol (PEG). In one embodiment, the pharmaceuticalcomposition that comprises the immunoglobulin disclosed herein may be ina water-soluble form, such as being present as pharmaceuticallyacceptable salts, which is meant to include both acid and base additionsalts. “Pharmaceutically acceptable acid addition salt” refers to thosesalts that retain the biological effectiveness of the free bases andthat are not biologically or otherwise undesirable, formed withinorganic acids such as hydrochloric acid, hydrobromic acid, sulfuricacid, nitric acid, phosphoric acid and the like, and organic acids suchas acetic acid, propionic acid, glycolic acid, pyruvic acid, oxalicacid, maleic acid, malonic acid, succinic acid, fumaric acid, tartaricacid, citric acid, benzoic acid, cinnamic acid, mandelic acid,methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid,salicylic acid and the like. “Pharmaceutically acceptable base additionsalts” include those derived from inorganic bases such as sodium,potassium, lithium, ammonium, calcium, magnesium, iron, zinc, copper,manganese, aluminum salts and the like. Some embodiments include atleast one of the ammonium, potassium, sodium, calcium, and magnesiumsalts. Salts derived from pharmaceutically acceptable organic non-toxicbases include salts of primary, secondary, and tertiary amines,substituted amines including naturally occurring substituted amines,cyclic amines and basic ion exchange resins, such as isopropylamine,trimethylamine, diethylamine, triethylamine, tripropylamine, andethanolamine. The formulations to be used for in vivo administration maybe sterile. This is readily accomplished by filtration through sterilefiltration membranes or other methods.

The immunoglobulins disclosed herein may also be formulated asimmunoliposomes. A liposome is a small vesicle comprising various typesof lipids, phospholipids and/or surfactant that is useful for deliveryof a therapeutic agent to a mammal. Liposomes containing theimmunoglobulin are prepared by methods known in the art, such asdescribed in Epstein et al., 1985, Proc Natl Acad Sci USA, 82:3688;Hwang et al., 1980, Proc Natl Acad Sci USA, 77:4030; U.S. Pat. No.4,485,045; U.S. Pat. No. 4,544,545; and PCT WO 97/38731, allincorporated entirely by reference. Liposomes with enhanced circulationtime are disclosed in U.S. Pat. No. 5,013,556, incorporated entirely byreference. The components of the liposome are commonly arranged in abilayer formation, similar to the lipid arrangement of biologicalmembranes. Particularly useful liposomes can be generated by the reversephase evaporation method with a lipid composition comprisingphosphatidylcholine, cholesterol and PEG-derivatizedphosphatidylethanolamine (PEG-PE). Liposomes are extruded throughfilters of defined pore size to yield liposomes with the desireddiameter. A chemotherapeutic agent or other therapeutically active agentis optionally contained within the liposome (Gabizon et al., 1989, JNational Cancer Inst 81:1484, incorporated entirely by reference).

The immunoglobulin and other therapeutically active agents may also beentrapped in microcapsules prepared by methods including but not limitedto coacervation techniques, interfacial polymerization (for exampleusing hydroxymethylcellulose or gelatin-microcapsules, orpoly-(methylmethacylate) microcapsules), colloidal drug delivery systems(for example, liposomes, albumin microspheres, microemulsions,nano-particles and nanocapsules), and macroemulsions. Such techniquesare disclosed in Remington's Pharmaceutical Sciences 16th edition, Osol,A. Ed., 1980, incorporated entirely by reference. Sustained-releasepreparations may be prepared. Suitable examples of sustained-releasepreparations include semipermeable matrices of solid hydrophobicpolymer, which matrices are in the form of shaped articles, e.g. films,or microcapsules. Examples of sustained-release matrices includepolyesters, hydrogels (for example poly(2-hydroxyethyl-methacrylate), orpoly(vinylalcohol)), polylactides (U.S. Pat. No. 3,773,919, incorporatedentirely by reference), copolymers of L-glutamic acid and gammaethyl-L-glutamate, non-degradable ethylene-vinyl acetate, degradablelactic acid-glycolic acid copolymers such as the Lupron Depot® (whichare injectable microspheres composed of lactic acid-glycolic acidcopolymer and leuprolide acetate), poly-D-(−)-3-hydroxybutyric acid, andProLease® (commercially available from Alkermes), which is amicrosphere-based delivery system composed of the desired bioactivemolecule incorporated into a matrix of poly-DL-lactide-co-glycolide(PLG).

Administration

Administration of the pharmaceutical composition comprising animmunoglobulin disclosed herein, e.g., in the form of a sterile aqueoussolution, may be done in a variety of ways, including, but not limitedto orally, subcutaneously, intravenously, intranasally, intraotically,transdermally, topically (e.g., gels, salves, lotions, creams, etc.),intraperitoneally, intramuscularly, intrapulmonary, vaginally,parenterally, rectally, or intraocularly. In some instances, for examplefor the treatment of wounds, inflammation, etc., the immunoglobulin maybe directly applied as a solution or spray. As is known in the art, thepharmaceutical composition may be formulated accordingly depending uponthe manner of introduction.

Subcutaneous administration may be used in circumstances where thepatient may self-administer the pharmaceutical composition. Many proteintherapeutics are not sufficiently potent to allow for formulation of atherapeutically effective dose in the maximum acceptable volume forsubcutaneous administration. This problem may be addressed in part bythe use of protein formulations comprising arginine-HCl, histidine, andpolysorbate (see WO 04091658, incorporated entirely by reference).Antibodies disclosed herein may be more amenable to subcutaneousadministration due to, for example, increased potency, improved serumhalf-life, or enhanced solubility.

As is known in the art, protein therapeutics are often delivered by IVinfusion or bolus. The antibodies disclosed herein may also be deliveredusing such methods. For example, administration may be by intravenousinfusion with 0.9% sodium chloride as an infusion vehicle.

Pulmonary delivery may be accomplished using an inhaler or nebulizer anda formulation comprising an aerosolizing agent. For example, AERx®inhalable technology commercially available from Aradigm, or Inhance™pulmonary delivery system commercially available from NektarTherapeutics may be used. Antibodies disclosed herein may be moreamenable to intrapulmonary delivery. FcRn is present in the lung, andmay promote transport from the lung to the bloodstream (e.g. Syntonix WO04004798, Bitonti et al. (2004) Proc. Nat. Acad. Sci. 101:9763-8, bothincorporated entirely by reference). Accordingly, antibodies that bindFcRn more effectively in the lung or that are released more efficientlyin the bloodstream may have improved bioavailability followingintrapulmonary administration. Antibodies disclosed herein may also bemore amenable to intrapulmonary administration due to, for example,improved solubility or altered isoelectric point.

Furthermore, immunoglobulins disclosed herein may be more amenable tooral delivery due to, for example, improved stability at gastric pH andincreased resistance to proteolysis. Furthermore, FcRn appears to beexpressed in the intestinal epithelia of adults (Dickinson et al. (1999)J. Clin. Invest. 104:903-11, incorporated entirely by reference), soantibodies disclosed herein with improved FcRn interaction profiles mayshow enhanced bioavailability following oral administration. FcRnmediated transport of antibodies may also occur at other mucus membranessuch as those in the gastrointestinal, respiratory, and genital tracts(Yoshida et al. (2004) Immunity 20:769-83, incorporated entirely byreference).

In addition, any of a number of delivery systems are known in the artand may be used to administer the antibodies disclosed herein. Examplesinclude, but are not limited to, encapsulation in liposomes,microparticles, microspheres (e.g., PLA/PGA microspheres), and the like.Alternatively, an implant of a porous, non-porous, or gelatinousmaterial, including membranes or fibers, may be used. Sustained releasesystems may comprise a polymeric material or matrix such as polyesters,hydrogels, poly(vinylalcohol), polylactides, copolymers of L-glutamicacid and ethyl-L-gutamate, ethylene-vinyl acetate, lactic acid-glycolicacid copolymers such as the Lupron Depot®, andpoly-D-(−)-3-hydroxyburyric acid. It is also possible to administer anucleic acid encoding an immunoglobulin disclosed herein, for example byretroviral infection, direct injection, or coating with lipids, cellsurface receptors, or other transfection agents. In all cases,controlled release systems may be used to release the immunoglobulin ator close to the desired location of action.

Dosing

The dosing amounts and frequencies of administration are, in oneembodiment, selected to be therapeutically or prophylacticallyeffective. As is known in the art, adjustments for protein degradation,systemic versus localized delivery, and rate of new protease synthesis,as well as the age, body weight, general health, sex, diet, time ofadministration, drug interaction and the severity of the condition maybe necessary, and will be ascertainable with routine experimentation bythose skilled in the art.

The concentration of the therapeutically active immunoglobulin in theformulation may vary from about 0.1 to 100 weight %. In one embodiment,the concentration of the immunoglobulin is in the range of 0.003 to 1.0molar. In order to treat a patient, a therapeutically effective dose ofthe immunoglobulin disclosed herein may be administered. By“therapeutically effective dose” herein is meant a dose that producesthe effects for which it is administered. The exact dose will depend onthe purpose of the treatment, and will be ascertainable by one skilledin the art using known techniques. Dosages may range from 0.0001 to 100mg/kg of body weight or greater, for example 0.1, 1, 10, or 50 mg/kg ofbody weight. In one embodiment, dosages range from 1 to 10 mg/kg.

In some embodiments, only a single dose of the immunoglobulin is used.In other embodiments, multiple doses of the immunoglobulin areadministered. The elapsed time between administrations may be less than1 hour, about 1 hour, about 1-2 hours, about 2-3 hours, about 3-4 hours,about 6 hours, about 12 hours, about 24 hours, about 48 hours, about 2-4days, about 4-6 days, about 1 week, about 2 weeks, or more than 2 weeks.

In other embodiments the antibodies disclosed herein are administered inmetronomic dosing regimes, either by continuous infusion or frequentadministration without extended rest periods. Such metronomicadministration may involve dosing at constant intervals without restperiods. Typically such regimens encompass chronic low-dose orcontinuous infusion for an extended period of time, for example 1-2days, 1-2 weeks, 1-2 months, or up to 6 months or more. The use of lowerdoses may minimize side effects and the need for rest periods.

In certain embodiments the immunoglobulin disclosed herein and one ormore other prophylactic or therapeutic agents are cyclicallyadministered to the patient. Cycling therapy involves administration ofa first agent at one time, a second agent at a second time, optionallyadditional agents at additional times, optionally a rest period, andthen repeating this sequence of administration one or more times. Thenumber of cycles is typically from 2-10. Cycling therapy may reduce thedevelopment of resistance to one or more agents, may minimize sideeffects, or may improve treatment efficacy.

Combination Therapies

The antibodies disclosed herein may be administered concomitantly withone or more other therapeutic regimens or agents. The additionaltherapeutic regimes or agents may be used to improve the efficacy orsafety of the immunoglobulin. Also, the additional therapeutic regimesor agents may be used to treat the same disease or a comorbidity ratherthan to alter the action of the immunoglobulin. For example, animmunoglobulin disclosed herein may be administered to the patient alongwith chemotherapy, radiation therapy, or both chemotherapy and radiationtherapy. The immunoglobulin disclosed herein may be administered incombination with one or more other prophylactic or therapeutic agents,including but not limited to cytotoxic agents, chemotherapeutic agents,cytokines, growth inhibitory agents, anti-hormonal agents, kinaseinhibitors, anti-angiogenic agents, cardioprotectants, immunostimulatoryagents, immunosuppressive agents, agents that promote proliferation ofhematological cells, angiogenesis inhibitors, protein tyrosine kinase(PTK) inhibitors, additional antibodies, FcγRIIb or other Fc receptorinhibitors, or other therapeutic agents.

The terms “in combination with” and “co-administration” are not limitedto the administration of said prophylactic or therapeutic agents atexactly the same time. Instead, it is meant that the immunoglobulindisclosed herein and the other agent or agents are administered in asequence and within a time interval such that they may act together toprovide a benefit that is increased versus treatment with only eitherthe immunoglobulin disclosed herein or the other agent or agents. Insome embodiments, immunoglobulins disclosed herein and the other agentor agents act additively, and sometimes synergistically. Such moleculesare suitably present in combination in amounts that are effective forthe purpose intended. The skilled medical practitioner can determineempirically, or by considering the pharmacokinetics and modes of actionof the agents, the appropriate dose or doses of each therapeutic agent,as well as the appropriate timings and methods of administration.

In one embodiment, the antibodies disclosed herein are administered withone or more additional molecules comprising antibodies or Fc. Theantibodies disclosed herein may be co-administered with one or moreother antibodies that have efficacy in treating the same disease or anadditional comorbidity; for example two antibodies may be administeredthat recognize two antigens that are overexpressed in a given type ofcancer, or two antigens that mediate pathogenesis of an autoimmune orinfectious disease.

Examples of anti-cancer antibodies that may be co-administered include,but are not limited to, anti-17-1A cell surface antigen antibodies suchas Panorex™ (edrecolomab); anti-4-1BB antibodies; anti-4Dc antibodies;anti-A33 antibodies such as A33 and CDP-833; anti-α4β1 integrinantibodies such as natalizumab; anti-α4β7 integrin antibodies such asLDP-02; anti-αVβ1 integrin antibodies such as F-200, M-200, and SJ-749;anti-αVβ3 integrin antibodies such as abciximab, CNTO-95, Mab-17E6, andVitaxin™, anti-complement factor 5 (C5) antibodies such as 5G1.1;anti-CA125 antibodies such as OvaRex® (oregovomab); anti-CD3 antibodiessuch as Nuvion® (visilizumab) and Rexomab; anti-CD4 antibodies such asIDEC-151, MDX-CD4, OKT4A; anti-CD6 antibodies such as Oncolysin B andOncolysin CD6; anti-CD7 antibodies such as HB2; anti-CD19 antibodiessuch as B43, MT-103, and Oncolysin B; anti-CD20 antibodies such as 2H7,2H7.v16, 2H7.v114, 2H7.v115, Bexxar® (tositumomab, I-131 labeledanti-CD20), Rituxan® (rituximab), and Zevalin® (Ibritumomab tiuxetan,Y-90 labeled anti-CD20); anti-CD22 antibodies such as Lymphocide™(epratuzumab, Y-90 labeled anti-CD22); anti-CD23 antibodies such asIDEC-152; anti-CD25 antibodies such as basiliximab and Zenapax®(daclizumab); anti-CD30 antibodies such as AC10, MDX-060, and SGN-30;anti-CD33 antibodies such as Mylotarg® (gemtuzumab ozogamicin),Oncolysin M, and Smart M195; anti-CD38 antibodies; anti-CD40 antibodiessuch as SGN-40 and toralizumab; anti-CD40L antibodies such as 5c8,Antova™, and IDEC-131; anti-CD44 antibodies such as bivatuzumab;anti-CD46 antibodies; anti-CD52 antibodies such as Campath®(alemtuzumab); anti-CD55 antibodies such as SC-1; anti-CD56 antibodiessuch as huN901-DM1; anti-CD64 antibodies such as MDX-33; anti-CD66eantibodies such as XR-303; anti-CD74 antibodies such as IMMU-110;anti-CD80 antibodies such as galiximab and IDEC-114; anti-CD89antibodies such as MDX-214; anti-CD123 antibodies; anti-CD138 antibodiessuch as B-B4-DM1; anti-CD146 antibodies such as AA-98; anti-CD148antibodies; anti-CEA antibodies such as cT84.66, labetuzumab, andPentacea™, anti-CTLA-4 antibodies such as MDX-101; anti-CXCR4antibodies; anti-EGFR antibodies such as ABX-EGF, Erbitux® (cetuximab),IMC-C225, and Merck Mab 425; anti-EpCAM antibodies such as Crucell'santi-EpCAM, ING-1, and IS-IL-2; anti-ephrin B2/EphB4 antibodies;anti-Her2 antibodies such as Herceptin®, MDX-210; anti-FAP (fibroblastactivation protein) antibodies such as sibrotuzumab; anti-ferritinantibodies such as NXT-211; anti-FGF-1 antibodies; anti-FGF-3antibodies; anti-FGF-8 antibodies; anti-FGFR antibodies, anti-fibrinantibodies; anti-G250 antibodies such as WX-G250 and Rencarex®; anti-GD2ganglioside antibodies such as EMD-273063 and TriGem; anti-GD3ganglioside antibodies such as BEC2, KW-2871, and mitumomab;anti-gpIIb/IIIa antibodies such as ReoPro; anti-heparinase antibodies;anti-Her2/ErbB2 antibodies such as Herceptin® (trastuzumab), MDX-210,and pertuzumab; anti-HLA antibodies such as Oncolym®, Smart 1D10;anti-HM1.24 antibodies; anti-ICAM antibodies such as ICM3; anti-IgAreceptor antibodies; anti-IGF-1 antibodies such as CP-751871 and EM-164;anti-IGF-1R antibodies such as IMC-A12; anti-IL-6 antibodies such asCNTO-328 and elsilimomab; anti-IL-15 antibodies such as HuMax™-IL15;anti-KDR antibodies; anti-laminin 5 antibodies; anti-Lewis Y antigenantibodies such as Hu3S193 and IGN-311; anti-MCAM antibodies; anti-Mudantibodies such as BravaRex and TriAb; anti-NCAM antibodies such asERIC-1 and ICRT; anti-PEM antigen antibodies such as Theragyn andTherex; anti-PSA antibodies; anti-PSCA antibodies such as IG8; anti-Ptkantibodies; anti-PTN antibodies; anti-RANKL antibodies such as AMG-162;anti-RLIP76 antibodies; anti-SK-1 antigen antibodies such as MonopharmC; anti-STEAP antibodies; anti-TAG72 antibodies such as CC49-SCA andMDX-220; anti-TGF-β antibodies such as CAT-152; anti-TNF-α antibodiessuch as CDP571, CDP870, D2E7, Humira® (adalimumab), and Remicade®(infliximab); anti-TRAIL-R1 and TRAIL-R2 antibodies; anti-VE-cadherin-2antibodies; and anti-VLA-4 antibodies such as Antegren™. Furthermore,anti-idiotype antibodies including but not limited to the GD3 epitopeantibody BEC2 and the gp72 epitope antibody 105AD7, may be used. Inaddition, bispecific antibodies including but not limited to theanti-CD3/CD20 antibody Bi20 may be used.

Examples of antibodies that may be co-administered to treat autoimmuneor inflammatory disease, transplant rejection, GVHD, and the likeinclude, but are not limited to, anti-α4β7 integrin antibodies such asLDP-02, anti-beta2 integrin antibodies such as LDP-01, anti-complement(C5) antibodies such as 5G1.1, anti-CD2 antibodies such as BTI-322,MEDI-507, anti-CD3 antibodies such as OKT3, SMART anti-CD3, anti-CD4antibodies such as IDEC-151, MDX-CD4, OKT4A, anti-CD11a antibodies,anti-CD14 antibodies such as IC14, anti-CD18 antibodies, anti-CD23antibodies such as IDEC 152, anti-CD25 antibodies such as Zenapax,anti-CD40L antibodies such as 5c8, Antova, IDEC-131, anti-CD64antibodies such as MDX-33, anti-CD80 antibodies such as IDEC-114,anti-CD147 antibodies such as ABX-CBL, anti-E-selectin antibodies suchas CDP850, anti-gpIIb/IIIa antibodies such as ReoPro/Abcixima,anti-ICAM-3 antibodies such as ICM3, anti-ICE antibodies such as VX-740,anti-FcγR1 antibodies such as MDX-33, anti-IgE antibodies such asrhuMab-E25, anti-IL-4 antibodies such as SB-240683, anti-IL-5 antibodiessuch as SB-240563, SCH55700, anti-IL-8 antibodies such as ABX-IL8,anti-interferon gamma antibodies, and anti-TNFa antibodies such asCDP571, CDP870, D2E7, Infliximab, MAK-195F, anti-VLA-4 antibodies suchas Antegren. Examples of other Fc-containing molecules that may beco-administered to treat autoimmune or inflammatory disease, transplantrejection, GVHD, and the like include, but are not limited to, the p75TNF receptor/Fc fusion Enbrel® (etanercept) and Regeneron's IL-1 trap.

Examples of antibodies that may be co-administered to treat infectiousdiseases include, but are not limited to, anti-anthrax antibodies suchas ABthrax, anti-CMV antibodies such as CytoGam and sevirumab,anti-cryptosporidium antibodies such as CryptoGAM, Sporidin-G,anti-helicobacter antibodies such as Pyloran, anti-hepatitis Bantibodies such as HepeX-B, Nabi-HB, anti-HIV antibodies such asHRG-214, anti-RSV antibodies such as felvizumab, HNK-20, palivizumab,RespiGam, and anti-staphylococcus antibodies such as Aurexis, Aurograb,BSYX-A110, and SE-Mab.

Alternatively, the antibodies disclosed herein may be co-administered orwith one or more other molecules that compete for binding to one or moreFc receptors. For example, co-administering inhibitors of the inhibitoryreceptor FcγRIIb may result in increased effector function. Similarly,co-administering inhibitors of the activating receptors such as FcγRIIIamay minimize unwanted effector function. Fc receptor inhibitors include,but are not limited to, Fc molecules that are engineered to act ascompetitive inhibitors for binding to FcγRIIb FcγRIIIa, or other Fcreceptors, as well as other immunoglobulins and specifically thetreatment called IVIg (intravenous immunoglobulin). In one embodiment,the inhibitor is administered and allowed to act before theimmunoglobulin is administered. An alternative way of achieving theeffect of sequential dosing would be to provide an immediate releasedosage form of the Fc receptor inhibitor and then a sustained releaseformulation of an immunoglobulin disclosed herein. The immediate releaseand controlled release formulations could be administered separately orbe combined into one unit dosage form. Administration of an FcγRIIbinhibitor may also be used to limit unwanted immune responses, forexample anti-Factor VIII antibody response following Factor VIIIadministration to hemophiliacs.

In one embodiment, the antibodies disclosed herein are administered witha chemotherapeutic agent. By “chemotherapeutic agent” as used herein ismeant a chemical compound useful in the treatment of cancer. Examples ofchemotherapeutic agents include but are not limited to alkylating agentssuch as thiotepa and cyclosphosphamide (CYTOXAN™); alkyl sulfonates suchas busulfan, improsulfan and piposulfan; androgens such as calusterone,dromostanolone propionate, epitiostanol, mepitiostane, testolactone;anti-adrenals such as aminoglutethimide, mitotane, trilostane;anti-androgens such as flutamide, nilutamide, bicalutamide, leuprolide,and goserelin; antibiotics such as aclacinomysins, actinomycin,authramycin, azaserine, bleomycins, cactinomycin, calicheamicin,carabicin, caminomycin, carzinophilin, chromomycins, dactinomycin,daunorubicin, detorubicin, 6-diazo-5-oxo-L-norleucine, doxorubicin,epirubicin, esorubicin, idarubicin, marcellomycin, mitomycins,mycophenolic acid, nogalamycin, olivomycins, peplomycin, potfiromycin,puromycin, quelamycin, rodorubicin, streptonigrin, streptozocin,tubercidin, ubenimex, zinostatin, zorubicin; anti estrogens includingfor example tamoxifen, raloxifene, aromatase inhibiting 4(5)-imidazoles,4-hydroxytamoxifen, trioxifene, keoxifene, LY 117018, onapristone, andtoremifene (Fareston); anti-metabolites such as methotrexate and5-fluorouracil (5-FU); folic acid analogues such as denopterin,methotrexate, pteropterin, trimetrexate; aziridines such as benzodopa,carboquone, meturedopa, and uredopa; ethylenimines and methylamelaminesincluding altretamine, triethylenemelamine, trietylenephosphoramide,triethylenethiophosphaoramide and trimethylolomelamine; folic acidreplenisher such as frolinic acid; nitrogen mustards such aschlorambucil, chlornaphazine, cholophosphamide, estramustine,ifosfamide, mechlorethamine, mechlorethamine oxide hydrochloride,melphalan, novembichin, phenesterine, prednimustine, trofosfamide,uracil mustard; nitrosureas such as carmustine, chlorozotocin,fotemustine, lomustine, nimustine, ranimustine; platinum analogs such ascisplatin and carboplatin; vinblastine; platinum; proteins such asarginine deiminase and asparaginase; purine analogs such as fludarabine,6-mercaptopurine, thiamiprine, thioguanine; pyrimidine analogs such asancitabine, azacitidine, 6-azauridine, carmofur, cytarabine,dideoxyuridine, doxifluridine, enocitabine, floxuridine, 5-FU; taxanes,e.g. paclitaxel (TAXOL®, Bristol-Myers Squibb Oncology, Princeton, N.J.)and docetaxel (TAXOTERE®, Rhne-Poulenc Rorer, Antony, France);topoisomerase inhibitor RFS 2000; thymidylate synthase inhibitor (suchas Tomudex); additional chemotherapeutics including aceglatone;aldophosphamide glycoside; aminolevulinic acid; amsacrine; bestrabucil;bisantrene; edatraxate; defofamine; demecolcine; diaziquone;difluoromethylornithine (DMFO); elformithine; elliptinium acetate;etoglucid; gallium nitrate; hydroxyurea; lentinan; lonidamine;mitoguazone; mitoxantrone; mopidamol; nitracrine; pentostatin; phenamet;pirarubicin; podophyllinic acid; 2-ethylhydrazide; procarbazine; PSK®;razoxane; sizofuran; spirogermanium; tenuazonic acid; triaziquone;2,2′,2″-trichlorotriethylamine; urethan; vindesine; dacarbazine;mannomustine; mitobronitol; mitolactol; pipobroman; gacytosine;arabinoside (“Ara-C”); cyclophosphamide; thiotepa; chlorambucil;gemcitabine; 6-thioguanine; mercaptopurine; methotrexate; etoposide(VP-16); ifosfamide; mitomycin C; mitoxantrone; vincristine;vinorelbine; navelbine; novantrone; teniposide; daunomycin; aminopterin;xeloda; ibandronate; CPT-11; retinoic acid; esperamicins; capecitabine.Pharmaceutically acceptable salts, acids or derivatives of any of theabove may also be used.

A chemotherapeutic or other cytotoxic agent may be administered as aprodrug. By “prodrug” as used herein is meant a precursor or derivativeform of a pharmaceutically active substance that is less cytotoxic totumor cells compared to the parent drug and is capable of beingenzymatically activated or converted into the more active parent form.See, for example Wilman, 1986, Biochemical Society Transactions, 615thMeeting Belfast, 14:375-382; Stella et al., “Prodrugs: A ChemicalApproach to Targeted Drug Delivery,” Directed Drug Delivery; andBorchardt et al., (ed.): 247-267, Humana Press, 1985, all incorporatedentirely by reference. The prodrugs that may find use withimmunoglobulins disclosed herein include but are not limited tophosphate-containing prodrugs, thiophosphate-containing prodrugs,sulfate-containing prodrugs, peptide-containing prodrugs, D-aminoacid-modified prodrugs, glycosylated prodrugs, beta-lactam-containingprodrugs, optionally substituted phenoxyacetamide-containing prodrugs oroptionally substituted phenylacetamide-containing prodrugs,5-fluorocytosine and other 5-fluorouridine prodrugs which can beconverted into the more active cytotoxic free drug. Examples ofcytotoxic drugs that can be derivatized into a prodrug form for use withthe antibodies disclosed herein include but are not limited to any ofthe aforementioned chemotherapeutic agents.

A variety of other therapeutic agents may find use for administrationwith the antibodies disclosed herein. In one embodiment, theimmunoglobulin is administered with an anti-angiogenic agent. By“anti-angiogenic agent” as used herein is meant a compound that blocks,or interferes to some degree, the development of blood vessels. Theanti-angiogenic factor may, for instance, be a small molecule or aprotein, for example an antibody, Fc fusion, or cytokine, that binds toa growth factor or growth factor receptor involved in promotingangiogenesis. In one embodiment, an anti-angiogenic factor may be anantibody that binds to Vascular Endothelial Growth Factor (VEGF). Otheragents that inhibit signaling through VEGF may also be used, for exampleRNA-based therapeutics that reduce levels of VEGF or VEGF-R expression,VEGF-toxin fusions, Regeneron's VEGF-trap, and antibodies that bindVEGF-R. In an alternate embodiment, the antibody is administered with atherapeutic agent that induces or enhances adaptive immune response, forexample an antibody that targets CTLA-4. Additional anti-angiogenesisagents include, but are not limited to, angiostatin (plasminogenfragment), antithrombin III, angiozyme, ABT-627, Bay 12-9566, benefin,bevacizumab, bisphosphonates, BMS-275291, cartilage-derived inhibitor(CD), CAI, CD59 complement fragment, CEP-7055, Col 3, combretastatinA-4, endostatin (collagen XVIII fragment), farnesyl transferaseinhibitors, fibronectin fragment, gro-beta, halofuginone, heparinases,heparin hexasaccharide fragment, HMV833, human chorionic gonadotropin(hCG), IM-862, interferon alpha, interferon beta, interferon gamma,interferon inducible protein 10 (IP-10), interleukin-12, kringle 5(plasminogen fragment), marimastat, metalloproteinase inhibitors (eg.TIMPs), 2-methodyestradiol, MMI 270 (CGS 27023A), plasminogen activiatorinhibitor (PAI), platelet factor-4 (PF4), prinomastat, prolactin 16 kDafragment, proliferin-related protein (PRP), PTK 787/ZK 222594,retinoids, solimastat, squalamine, SS3304, SU5416, SU6668, SU11248,tetrahydrocortisol-S, tetrathiomolybdate, thalidomide, thrombospondin-1(TSP-1), TNP-470, transforming growth factor beta (TGF-β),vasculostatin, vasostatin (calreticulin fragment), ZS6126, and ZD6474.

In one embodiment, the immunoglobulin is administered with a tyrosinekinase inhibitor. By “tyrosine kinase inhibitor” as used herein is meanta molecule that inhibits to some extent tyrosine kinase activity of atyrosine kinase. Examples of such inhibitors include but are not limitedto quinazolines, such as PD 153035, 4-(3-chloroanilino) quinazoline;pyridopyrimidines; pyrimidopyrimidines; pyrrolopyrimidines, such as CGP59326, CGP 60261 and CGP 62706; pyrazolopyrimidines,4-(phenylamino)-7H-pyrrolo(2,3-d) pyrimidines; curcumin (diferuloylmethane, 4,5-bis (4-fluoroanilino)phthalimide); tyrphostines containingnitrothiophene moieties; PD-0183805 (Warner-Lambert); antisensemolecules (e.g. those that bind to ErbB-encoding nucleic acid);quinoxalines (U.S. Pat. No. 5,804,396); tryphostins (U.S. Pat. No.5,804,396); ZD6474 (Astra Zeneca); PTK-787 (Novartis/Schering A G);pan-ErbB inhibitors such as C1-1033 (Pfizer); Affinitac (ISIS 3521;Isis/Lilly); Imatinib mesylate (ST1571, Gleevec®; Novartis); PKI 166(Novartis); GW2016 (Glaxo SmithKline); C1-1033 (Pfizer); EKB-569(Wyeth); Semaxinib (Sugen); ZD6474 (AstraZeneca); PTK-787(Novartis/Schering AG); INC-1C11 (Imclone); or as described in any ofthe following patent publications: U.S. Pat. No. 5,804,396; PCT WO99/09016 (American Cyanimid); PCT WO 98/43960 (American Cyanamid); PCTWO 97/38983 (Warner-Lambert); PCT WO 99/06378 (Warner-Lambert); PCT WO99/06396 (Warner-Lambert); PCT WO 96/30347 (Pfizer, Inc); PCT WO96/33978 (AstraZeneca); PCT WO96/3397 (AstraZeneca); PCT WO 96/33980(AstraZeneca), gefitinib (IRESSA™, ZD1839, AstraZeneca), and OSI-774(Tarceva™, OSI Pharmaceuticals/Genentech), all patent publicationsincorporated entirely by reference.

In another embodiment, the immunoglobulin is administered with one ormore immunomodulatory agents. Such agents may increase or decreaseproduction of one or more cytokines, up- or down-regulate self-antigenpresentation, mask MHC antigens, or promote the proliferation,differentiation, migration, or activation state of one or more types ofimmune cells. Immunomodulatory agents include but not limited to:non-steroidal anti-inflammatory drugs (NSAIDs) such as asprin,ibuprofed, celecoxib, diclofenac, etodolac, fenoprofen, indomethacin,ketoralac, oxaprozin, nabumentone, sulindac, tolmentin, rofecoxib,naproxen, ketoprofen, and nabumetone; steroids (eg. glucocorticoids,dexamethasone, cortisone, hydroxycortisone, methylprednisolone,prednisone, prednisolone, trimcinolone, azulfidineicosanoids such asprostaglandins, thromboxanes, and leukotrienes; as well as topicalsteroids such as anthralin, calcipotriene, clobetasol, and tazarotene);cytokines such as TGFb, IFNa, IFNb, IFNg, IL-2, IL-4, IL-10; cytokine,chemokine, or receptor antagonists including antibodies, solublereceptors, and receptor-Fc fusions against BAFF, B7, CCR2, CCR5, CD2,CD3, CD4, CD6, CD7, CD8, CD11, CD14, CD15, CD17, CD18, CD20, CD23, CD28,CD40, CD40L, CD44, CD45, CD52, CD64, CD80, CD86, CD147, CD152,complement factors (C5, D) CTLA4, eotaxin, Fas, ICAM, ICOS, IFNα, IFNβ,IFNγ, IFNAR, IgE, IL-1, IL-2, IL-2R, IL-4, IL-5R, IL-6, IL-8, IL-9IL-12, IL-13, IL-13R1, IL-15, IL-18R, IL-23, integrins, LFA-1, LFA-3,MHC, selectins, TGFβ, TNFα, TNFβ, TNF-R1, T-cell receptor, includingEnbrel® (etanercept), Humira® (adalimumab), and Remicade® (infliximab);heterologous anti-lymphocyte globulin; other immunomodulatory moleculessuch as 2-amino-6-aryl-5 substituted pyrimidines, anti-idiotypicantibodies for MHC binding peptides and MHC fragments, azathioprine,brequinar, bromocryptine, cyclophosphamide, cyclosporine A,D-penicillamine, deoxyspergualin, FK506, glutaraldehyde, gold,hydroxychloroquine, leflunomide, malononitriloamides (eg. leflunomide),methotrexate, minocycline, mizoribine, mycophenolate mofetil, rapamycin,and sulfasasazine.

In an alternate embodiment, immunoglobulins disclosed herein areadministered with a cytokine. By “cytokine” as used herein is meant ageneric term for proteins released by one cell population that act onanother cell as intercellular mediators. Examples of such cytokines arelymphokines, monokines, and traditional polypeptide hormones. Includedamong the cytokines are growth hormone such as human growth hormone,N-methionyl human growth hormone, and bovine growth hormone; parathyroidhormone; thyroxine; insulin; proinsulin; relaxin; prorelaxin;glycoprotein hormones such as follicle stimulating hormone (FSH),thyroid stimulating hormone (TSH), and luteinizing hormone (LH); hepaticgrowth factor; fibroblast growth factor; prolactin; placental lactogen;tumor necrosis factor-alpha and -beta; mullerian-inhibiting substance;mouse gonadotropin-associated peptide; inhibin; activin; vascularendothelial growth factor; integrin; thrombopoietin (TPO); nerve growthfactors such as NGF-beta; platelet-growth factor; transforming growthfactors (TGFs) such as TGF-alpha and TGF-beta; insulin-like growthfactor-I and -II; erythropoietin (EPO); osteoinductive factors;interferons such as interferon-alpha, beta, and -gamma; colonystimulating factors (CSFs) such as macrophage-CSF (M-CSF);granulocyte-macrophage-CSF (GM-CSF); and granulocyte-CSF (G-CSF);interleukins (ILs) such as IL-1, IL-1alpha, IL-2, IL-3, IL-4, IL-5,IL-6, IL-7, IL-8, IL-9, IL-10, IL-11, IL-12; IL-15, a tumor necrosisfactor such as TNF-alpha or TNF-beta; and other polypeptide factorsincluding LIF and kit ligand (KL). As used herein, the term cytokineincludes proteins from natural sources or from recombinant cell culture,and biologically active equivalents of the native sequence cytokines.

In one embodiment, cytokines or other agents that stimulate cells of theimmune system are co-administered with the immunoglobulin disclosedherein. Such a mode of treatment may enhance desired effector function.For example, agents that stimulate NK cells, including but not limitedto IL-2 may be co-administered. In another embodiment, agents thatstimulate macrophages, including but not limited to C5a, formyl peptidessuch as N-formyl-methionyl-leucyl-phenylalanine (Beigier-Bompadre et al.(2003) Scand. J. Immunol. 57: 221-8, incorporated entirely byreference), may be co-administered. Also, agents that stimulateneutrophils, including but not limited to G-CSF, GM-CSF, and the likemay be administered. Furthermore, agents that promote migration of suchimmunostimulatory cytokines may be used. Also additional agentsincluding but not limited to interferon gamma, IL-3 and IL-7 may promoteone or more effector functions.

In an alternate embodiment, cytokines or other agents that inhibiteffector cell function are co-administered with the immunoglobulindisclosed herein. Such a mode of treatment may limit unwanted effectorfunction.

In an additional embodiment, the immunoglobulin is administered with oneor more antibiotics, including but not limited to: aminoglycosideantibiotics (e.g. apramycin, arbekacin, bambermycins, butirosin,dibekacin, gentamicin, kanamycin, neomycin, netilmicin, paromomycin,ribostamycin, sisomycin, spectrinomycin), aminocyclitols (eg.sprctinomycin), amphenicol antibiotics (eg. azidamfenicol,chloramphenicol, florfrnicol, and thiamphemicol), ansamycin antibiotics(eg. rifamide and rifampin), carbapenems (eg. imipenem, meropenem,panipenem); cephalosporins (eg. cefaclor, cefadroxil, cefamandole,cefatrizine, cefazedone, cefozopran, cefpimizole, cefpiramide,cefpirome, cefprozil, cefuroxine, cefixime, cephalexin, cephradine),cephamycins (cefbuperazone, cefoxitin, cefminox, cefmetazole, andcefotetan); lincosamides (eg. clindamycin, lincomycin); macrolide (eg.azithromycin, brefeldin A, clarithromycin, erythromycin, roxithromycin,tobramycin), monobactams (eg. aztreonam, carumonam, and tigernonam);mupirocin; oxacephems (eg. flomoxef, latamoxef, and moxalactam);penicillins (eg. amdinocillin, amdinocillin pivoxil, amoxicillin,bacampicillin, bexzylpenicillinic acid, benzylpenicillin sodium,epicillin, fenbenicillin, floxacillin, penamecillin, penethamatehydriodide, penicillin o-benethamine, penicillin O, penicillin V,penicillin V benzoate, penicillin V hydrabamine, penimepicycline, andphencihicillin potassium); polypeptides (eg. bacitracin, colistin,polymixin B, teicoplanin, vancomycin); quinolones (amifloxacin,cinoxacin, ciprofloxacin, enoxacin, enrofloxacin, feroxacin, flumequine,gatifloxacin, gemifloxacin, grepafloxacin, lomefloxacin, moxifloxacin,nalidixic acid, norfloxacin, ofloxacin, oxolinic acid, pefloxacin,pipemidic acid, rosoxacin, rufloxacin, sparfloxacin, temafloxacin,tosufloxacin, trovafloxacin); rifampin; streptogramins (eg.quinupristin, dalfopristin); sulfonamides (sulfanilamide,sulfamethoxazole); tetracyclenes (chlortetracycline, demeclocyclinehydrochloride, demethylchlortetracycline, doxycycline, duramycin,minocycline, neomycin, oxytetracycline, streptomycin, tetracycline,vancomycin).

Anti-fungal agents such as amphotericin B, ciclopirox, clotrimazole,econazole, fluconazole, flucytosine, itraconazole, ketoconazole,niconazole, nystatin, terbinafine, terconazole, and tioconazole may alsobe used.

Antiviral agents including protease inhibitors, reverse transcriptaseinhibitors, and others, including type I interferons, viral fusioninhibitors, and neuramidase inhibitors, may also be used. Examples ofantiviral agents include, but are not limited to, acyclovir, adefovir,amantadine, amprenavir, clevadine, enfuvirtide, entecavir, foscarnet,gangcyclovir, idoxuridine, indinavir, lopinavir, pleconaril, ribavirin,rimantadine, ritonavir, saquinavir, trifluridine, vidarabine, andzidovudine, may be used.

The antibodies disclosed herein may be combined with other therapeuticregimens. For example, in one embodiment, the patient to be treated withan immunoglobulin disclosed herein may also receive radiation therapy.Radiation therapy can be administered according to protocols commonlyemployed in the art and known to the skilled artisan. Such therapyincludes but is not limited to cesium, iridium, iodine, or cobaltradiation. The radiation therapy may be whole body irradiation, or maybe directed locally to a specific site or tissue in or on the body, suchas the lung, bladder, or prostate. Typically, radiation therapy isadministered in pulses over a period of time from about 1 to 2 weeks.The radiation therapy may, however, be administered over longer periodsof time. For instance, radiation therapy may be administered to patientshaving head and neck cancer for about 6 to about 7 weeks. Optionally,the radiation therapy may be administered as a single dose or asmultiple, sequential doses. The skilled medical practitioner candetermine empirically the appropriate dose or doses of radiation therapyuseful herein. In accordance with another, an immunoglobulin disclosedherein and one or more other anti-cancer therapies are employed to treatcancer cells ex vivo. It is contemplated that such ex vivo treatment maybe useful in bone marrow transplantation and particularly, autologousbone marrow transplantation. For instance, treatment of cells ortissue(s) containing cancer cells with immunoglobulin and one or moreother anti-cancer therapies, such as described above, can be employed todeplete or substantially deplete the cancer cells prior totransplantation in a recipient patient.

It is of course contemplated that the antibodies disclosed herein mayemploy in combination with still other therapeutic techniques such assurgery or phototherapy.

EXAMPLES

Examples are provided below are for illustrative purposes only. Theseexamples are not meant to constrain any embodiment disclosed herein toany particular application or theory of operation.

Example 1 Novel Methods for Inhibiting FcγRIIb⁺ Cells

FcγRIIb is expressed on a variety of immune cells, including B cells,plasma cells, dendritic cells, monocytes, and macrophages, where itplays a critical role in immune regulation. In its normal role on Bcells, FcγRIIb serves as a feedback mechanism to modulate B cellactivation through the B cell receptor (BCR). Engagement of B cellantigen receptor (BCR) by immune complexed antigen on mature B cellsactivates an intracellular signaling cascade, including calciummobilization, which leads to cell proliferation and differentiation.However, as IgG antibodies with specificity to the antigen are produced,the associated immune complexes (ICs) can crosslink the BCR withFcγRIIb, whereupon the activation of BCR is inhibited by engagement ofFcγRIIb and associated intracellular signaling pathways that interferewith the downstream pathways of BCR activation.

B cells function not only to produce antibodies and cytokines thatcontrol immune response, they are also antigen presenting cells (APCs).Internalization of antigen by BCR into a B cell can play a role inpresentation to and activation of T cells. Regulation of B cellactivation through the BCR is also potentially regulated by antibodyengagement of FcγRIIb. Other APCs such as dendritic cells, macrophages,and monocytes, are capable of internalizing antibody-bound antigenthrough activating receptors such as FcγRIIa, FcγRIIIa, and FcγRI.Expression of FcγRIIb on these cell types, particularly dendritic cells,can inhibit activation of these cell types and subsequent presentationto and activation of T cells (Desai et al., 2007, J Immunol).

A novel strategy for inhibiting activation of the aforementioned celltypes it to use a single immunoglobulin to coengage FcγRIIb with surfaceantigen present on the FcγRIIb+ cell. In the case of B cells, based onthe natural biological mechanism, this would potentially involve dualtargeting of FcγRIIb and BCR, with the goal of mimicking immunecomplex-mediated suppression of B cell activation. FIG. 3 illustratesone such potential mechanism, in which an antibody is used to coengageboth FcγRIIb via its Fc region, and a target antigen associated with BCRcomplex, in this example CD19, via its Fv region.

Example 2 Engineering Immunoglobulins with Selectively Enhanced Affinityfor FcγRIIb

Under physiological conditions, bridging of the BCR with FcγRIIb andsubsequent B cell suppression occurs via immune complexes of IgGs andcognate antigen. The design strategy was to reproduce this effect usinga single crosslinking antibody. Human IgG binds human FcγRIIb with weakaffinity (approximately 1 μM for IgG1), and FcγRIIb-mediated inhibitionoccurs in response to immune-complexed but not monomeric IgG. It wasreasoned that increasing Fc affinity to this receptor would be requiredfor maximal inhibition of B cell activation. Protein engineering methodswere used to design and screen Fc variants for enhanced FcγRIIb binding.

In addition to this primary design goal (maximal Fc affinity toFcγRIIb), a secondary design goal was to reduce interaction of the Fcregion with activating FcγRs. FcγR affinity profiles that may be optimalfor inhibiting FcγRIIb cells include not only high affinity for theinhibitory receptor FcγRIIb, but also potentially high FcγRIIb affinitycoupled with reduced affinity for one or more activating receptors,including, for example, FcγRI, FcγRIIIa, and/or FcγRIIa. Reducedaffinity to activating receptors may lead to reduced toxicity associatedwith an antibody treatment. For example, reduced affinity to FcγRIIIa,present on NK cells, should reduce the level of NK cell-mediated ADCC.Similarly, reduced affinity to FcγRIIa, present on a variety of effectorcells including macrophages and neutrophils, should reduce the level ofphagocytosis (ADCP) mediated by these cells. In addition, for monocytes,macrophages, dendritic cells, and the like, reduced interaction withactivating FcγRs would mean that immunoglobulin would be more free tointeract with FcγRIIb on the cell surface.

Using solved structures of the human Fc/FcγRIIIb complex (and thesequences of the human FcγRs, structural and sequence analysis were usedto identify FcγR positions that contribute to FcγRIIb affinity andselectivity relative to the activating receptors. The design strategyemployed two steps. First, FcγR positions that are determinants ofFcγRIIb and FcγRIIIa binding selectivity were identified by accountingfor proximity to the FcγR/Fc interface and amino acid dissimilaritybetween FcγRIIb and FcγRIIIa. The results of this analysis are presentedin FIG. 4. Second, sequence positions in the Fc region proximal to theseFcγR positions were identified. The results of this analysis arepresented in FIG. 5. Fc variants were designed that incorporatesubstitutions at these positions.

A library of Fc variants was generated and screened to explore aminoacid modifications at these positions. Variants were generated andscreened in the context of an antibody targeting the antigen CD19, aregulatory component of the BCR coreceptor complex. The Fv region of thethis antibody is a humanized and affinity matured version of antibody4G7, and is referred to herein as HuAM4G7. The amino acid sequences ofthis antibody are provided in FIG. 54A-FIG. 54D. The Fv genes for thisantibody were subcloned into the mammalian expression vector pTT5(National Research Council Canada). Mutations in the Fc domain wereintroduced using site-directed mutagenesis (QuikChange, Stratagene,Cedar Creek, Tex.). In addition, control knock out variants with ablatedaffinity for Fc receptors were generated that comprise the substitutionL328R, and either a G236R substitution or an Arg inserted after position236. These variants (G236R/L328R and ^236R/L328R) are referred to asFc-KO or FcγR knockout. To serve as non-CD19 Fc isotype controls,anti-respiratory syncytial virus (RSV) and anti-FITC antibodies wereconstructed in the pTT5 vector by fusing the appropriate V_(L) and V_(H)regions to the C_(L)κ and C_(H)1-3 domains with Fc changes. Heavy andlight chain constructs were cotransfected into HEK293E cells forexpression, and antibodies were purified using protein A affinitychromatography (Pierce Biotechnology, Rockford, Ill.).

Human Fc receptor proteins FcγRI and FcγRIIb for binding and competitionstudies were obtained from R&D Systems (Minneapolis, Minn.). Genesencoding FcγRIIa and FcγRIIIa receptor proteins were obtained from theMammalian Gene Collection (ATCC), and subcloned into pTT5 vector(National Research Council Canada) containing 6×His and GST-tags.Allelic forms of the receptors (H131 and R131 for FcγRIIa and V158 andF158 for FcγRIIIa) were generated using QuikChange mutagenesis. Vectorsencoding the receptors were transfected into HEK293T cells, and proteinswere purified using nickel affinity chromatography.

Variants were screened for receptor affinity using Biacore™ technology,also referred to as Biacore herein, a surface plasmon resonance (SPR)based technology for studying biomolecular interactions in real time.SPR measurements were performed using a Biacore 3000 instrument(Biacore, Piscataway, N.J.). A protein NG (Pierce Biotechnology) CM5biosensor chip (Biacore) was generated using a standard primary aminecoupling protocol. All measurements were performed using HBS-EP buffer(10 mM HEPES pH 7.4, 0.15 M NaCl, 3 mM EDTA, 0.005% vol/vol surfactantP20, Biacore). Antibodies at 20 nM or 50 nM in HBS-EP buffer wereimmobilized on the protein NG surface and FcγRs were injected. Aftereach cycle, the surface was regenerated by injecting glycine buffer (10mM, pH 1.5). Data were processed by zeroing time and response before theinjection of FcγR and by subtracting appropriate nonspecific signals(response of reference channel and injection of running buffer). Kineticanalyses were performed by global fitting of binding data with a 1:1Langmuir binding model using BIAevaluation software (Biacore).

A representative set of sensorgrams for binding of select variantanti-CD19 antibodies to FcγRIIb is shown in FIG. 6. The affinities(equilibrium Kds) of all variants and WT (native) IgG1 to all of theFcγRs, obtained from fits of the Biacore binding data, are presented inFIG. 7A-FIG. 7D. Whereas WT IgG1 Fc binds with FcγRIIb with μM affinity(Kd=1467 nM in FIG. 7), a large number of variants have been engineeredthat bind more tightly. Because all of the antibodies tested havespecificity for CD19 (via their Fv region), the binding results in FIG.7A-FIG. 7D are due solely to binding to FcγRIIb by the Fc region. Thisis supported by the lack of detectable binding by the Fc-KO variants(G236R/L328R and ^236R/L328R), which are ablated for binding to allFcγRs.

A useful quantity for analysis of the variants is their fold affinityrelative to WT IgG1, which is generated by dividing the Kd for bindingof WT IgG1 by the Kd for binding of variant for each receptor. Thesefold affinity results are provided in FIG. 8A-FIG. 8D. A number ofvariants have FcγRIIb binding enhancements over 2 logs, andsubstantially reduced or ablated affinities for the activatingreceptors. In particular, S267E (single substitution) as well asL235Y/S267E, G236D/S267E, S239D/S267E, S267E/H268E, and S267E/L328F(double substitutions) have markedly higher affinity for FcγRIIb. Inaddition, these variant have affinity for the activating receptorFcγRIIIa that is either comparable to native IgG1, modestly enhanced, oreven significantly reduced.

FIG. 9 shows a plot of the FcγR affinities of select variants on a logscale, compared with those of WT IgG1. The variant with the highestaffinity for FcγRIIb, S267E/L328F, shows over 2 orders of magnitudeimprovement in affinity to FcγRIIb, and significantly reduced affinityto the activating receptors, including FcγRIIIa, FcγRI, and H131FcγRIIa.

The data in FIGS. 9 and 10 indicate that the properties of the variantsare highly dependent not only on the position that is mutated, but alsothe precise amino acid that is substituted at each position. Forexample, one of the strongest positions for controlling FcγRIIb affinityand selectivity relative to activating FcγRs is position 267. Yetmodification at this position can yield dramatically different resultsdepending on the particular amino acid that is substituted Inparticular, as shown in FIG. 10, whereas affinity of S267E for FcγRIIbis greatly enhanced relative to WT IgG1 and provides substantialselectivity improvement relative to FcγRIIIa, other substitutions suchas S267A and S267G provide either marginal or no FcγRIIb enhancement,and/or little or no selectivity improvement relative to FcγRIIIa. Theimportance of the precise modification is further supported by the factthat two of the best positions for selectively enhancing FcγRIIbaffinity, 236 and 328 (for example 236D and 328F) are also the samepositions that are modified to generate the Fc-KO variant (236R and328R). These results illustrate the complexity of the FcγR interface,and highlight the challenge of engineering modifications that preciselycontrol desired FcγR properties.

Many of the Fc combination variants, including double and triplecombinations of single substitutions, exhibited unexpected synergy(non-additivity) when compared against the single substitutions alone.This was determined (for all combination variants for which data wasavailable) by comparing the actual fold improvement in affinity asmeasured by Biacore versus the expected fold improvement in affinity ascalculated by the product of the fold improvements of the singlesubstitutions (FIG. 11). As can be seen from the data, doublesubstitutions at the following pairs of positions resulted in a greaterthan expected affinity for one or more FcγRs: 234/267, 235/267, 236/267,236/268, 239/267, 239/268, 266/267, 267/328, and 268/327.

In order to validate the Biacore data and evaluate receptor binding ofthe variants on the cell surface, binding of select antibodies to cellsexpressing FcγRIIb was measured. Since HEK293T cells do not express CD19or FcγRs, transfection of these cells with FcγRIIb allowed an analysisof antibody binding to Fc receptors in an isolated system on a cellsurface. HEK293T cells in DMEM with 10% FBS were transfected with humanFcγRIIb cDNA in pCMV6 expression vector (Origene Technologies,Rockville, Md.), cultured for 3 days, harvested, washed twice in PBS,resuspended in PBS with 0.1% BSA (PBS/BSA), and aliquoted at 2×105 cellsper well into 96-well microtiter plates. Fc variant antibodies wereserially diluted in PBS/BSA then added to the cells and incubated withmixing for 1 h at room temperature. After extensive washing withPBS/BSA, phycoerythrin (PE)-labeled anti-human-Fab-specific goat F(ab′)2fragment was added for detection. Cells were incubated for 30 min atroom temperature, washed, and resuspended in PBS/BSA. Binding wasevaluated using a FACSCanto II flow cytometer (BD Biosciences, San Jose,Calif.), and the mean fluorescence intensity (MFI) was plotted as afunction of antibody concentration using GraphPad Prism software(GraphPad Software, San Diego, Calif.) from which half-maximal binding(EC50) values were determined by sigmoidal dose response modeling.

Receptor expression levels were assessed prior to binding of antibodies,and half-maximal effective concentration (EC50) values of the MFI atdifferent antibody concentrations were determined. FIG. 12 shows theresults of this experiment. The EC50 values of the variants testedshowed a similar rank order as the Biacore results. The cell-surfacebinding confirmed that the S267E/L328F variant of those tested has thehighest affinity for FcγRIIb, with an EC50 approximately 320-foldrelative to WT IgG1. The strong agreement between these cell surfacebinding data and the Biacore binding data support the accuracy of theaffinity measurements.

Because of the importance of animal models in drug development, selectvariants were screened further for binding to mouse and cynomolgousmonkey receptors. The extracellular regions of mouse and cynologousmonkey (Macaca fascicularis) FcγRs were expressed and purified. Theextracellular regions of these receptors were obtained by PCR fromclones obtained from the Mammalian Gene Collection (MGC), or generatedde novo using recursive PCR. To enable purification and screening,receptors were fused C-terminally with a His- and GST-tag. Tagged FcγRswere transfected into 293T cells, and media containing secreted receptorwere harvested 3 days later and purified using Nickel chromatography.

Variant antibodies were tested for their affinity to mouse or cynologousmonkey FcγRs using Biacore SPR as described above. Specifically,antibodies were first immobilized on a protein A/G chip to high density,and then followed by injections of the extracellular domain of the mouseor cynologous monkey FcγR of interest. Both association and dissociationphases were tracked in real time using the Biacore technology. FIG.13A-FIG. 13D show the fold improvements (compared to WT IgG1) forbinding of select variants to mouse and cynologous monkey FcγRs asdetermined from Biacore.

Although the variants were screened in the context of human IgG1, it iscontemplated that the variants could be used in the context of otherantibody isotypes, for example including but not limited to human IgG2,human IgG3, and human IgG4 (FIG. 1). In order to explore thetransferability of the variants to other antibody isotypes, theS267E/L328F variant was constructed and tested in the context of aIgG1/2 ELLGG antibody, which is a variant of an IgG2 Fc region (U.S.Ser. No. 11/256,060, herein expressly incorporated by reference). Themutations were constructed, antibodies purified, and binding datacarried out as described above. FIG. 14 shows affinities of the IgG1 andIgG1/2 variant antibodies to the human FcγRs as determined by Biacore.The data indicate that the greatly enhanced FcγRIIb affinity and theoverall FcγR binding profile are maintained in the variant IgG2 Fcregion, thus supporting the use of the variants in other isotypecontexts.

Collectively, the above data indicate that a number of engineeredvariants, at specific Fc positions, provide the targeted properties,namely enhanced affinity for FcγRIIb, and selectively enhanced FcγRIIbaffinity relative to the activating receptors FcγRI, FcγRIIa, andFcγRIIIa. Substitutions to enhance affinity to FcγRIIb include: 234,235, 236, 237, 239, 266, 267, 268, 325, 326, 327, 328, and 332. In someembodiments, substitutions are made to at least one or more of thenonlimiting following positions to enhance affinity to FcγRIIb: 235,236, 239, 266, 267, 268, and 328.

Nonlimiting combinations of positions for making substitutions toenhance affinity to FcγRIIb include: 234/239, 234/267, 234/328, 235/236,235/239, 235/267, 235/268, 235/328, 236/239, 236/267, 236/268, 236/328,237/267, 239/267, 239/268, 239/327, 239/328, 239/332, 266/267, 267/268,267/325, 267/327, 267/328, 267/332, 268/327, 268/328, 268/332, 326/328,327/328, and 328/332. In some embodiments, combinations of positions formaking substitutions to enhance affinity to FcγRIIb include, but are notlimited to: 235/267, 236/267, 239/268, 239/267, 267/268, and 267/328.

Substitutions for enhancing affinity to FcγRIIb include: L234D, L234E,L234W, L235D, L235F, L235R, L235Y, G236D, G236N, G237D, G237N, S239D,S239E, V266M, S267D, S267E, H268D, H268E, A327D, A327E, L328F, L328W,L328Y, and 1332E. In some embodiments, combination of positions formaking substitutions for enhancing affinity to FcγRIIb include, but arenot limited to: L235Y, G236D, S239D, V266M, S267E, H268D, H268E, L328F,L328W, and L328Y.

Combinations of substitutions for enhancing affinity to FcγRIIb include:L234D/S267E, L234E/S267E, L234F/S267E, L234E/L328F, L234W/S239D,L234W/S239E, L234W/S267E, L234W/L328Y, L235D/S267E, L235D/L328F,L235F/S239D, L235F/S267E, L235F/L328Y, L235Y/G236D, L235Y/S239D,L235Y/S267D, L235Y/S267E, L235Y/H268E, L235Y/L328F, G236D/S239D,G236D/S267E, G236D/H268E, G236D/L328F, G236N/S267E, G237D/S267E,G237N/S267E, S239D/S267D, S239D/S267E, S239D/H268D, S239D/H268E,S239D/A327D, S239D/L328F, S239D/L328W, S239D/L328Y, S239D/I332E,S239E/S267E, V266M/S267E, S267D/H268E, S267E/H268D, S267E/H268E,S267E/N325L, S267E/A327D, S267E/A327E, S267E/L328F, S267E/L328I,S267E/L328Y, S267E/I332E, H268D/A327D, H268D/L328F, H268D/L328W,H268D/L328Y, H268D/1332E, H268E/L328F, H268E/L328Y, A327D/L328Y,L328F/1332E, L328W/1332E, and L328Y/1332E. In some embodiments,combinations of substitutions for enhancing affinity to FcγRIIb include,but are not limited to: L235Y/S267E, G236D/S267E, S239D/H268D,S239D/S267E, S267E/H268D, S267E/H268E, and S267E/L328F.

Example 3 Immunoglobulins Inhibit BCR-mediated Primary Human B CellViability

Although normal B cells have a long in vivo half life of approximatelyfive weeks, their lifespan is greatly reduced in vitro. BCR stimulationby crosslinking antibodies such as anti-IgM or anti-CD79b counteractsthis in vitro predisposition towards apoptosis, leading to B cellactivation and increased B cell viability. To demonstrate this, anATP-dependent B cell viability assay was performed. Human peripheralblood mononuclear cells (PBMCs) were purified from leukapheresis ofanonymous healthy volunteers (HemaCare, Van Nuys, Calif.) usingFicoll-Paque Plus density gradients (Amersham Biosciences, Newark,N.J.). Primary human B cells were purified from PBMCs using a B cellenrichment kit (StemCell Technologies, Vancouver, British Columbia).Murine anti-human CD79b (clone SN8) was purchased from Santa CruzBiotechnology (Santa Cruz, Calif.). Polyclonal anti-mu F(ab′)2 waspurchased from Jackson Immunoresearch Lab (West Grove, Pa.). Anti-mu oranti-CD79b antibody serial dilutions were performed in triplicate in96-well microtiter plates containing RPMI1640 with 10% FBS. Purifiedprimary human B cells (5-7.5×104 per well) were added to a final volumeof 100 μl, and incubated at 37° C. for 3 days. ATP-dependentluminescence was quantified to determine cell viability (Cell Titer-GloCell Viability Assay, Promega, Madison, Wis.) and a Topcount luminometer(PerkinElmer, Waltham, Mass.) was used for data acquisition. FIGS. 15Aand 15B show the results of the assay, demonstrating the survival ofprimary human B cells upon BCR activation, here carried out bycrosslinking with anti-mu (A) or anti-CD79b (B) antibodies. In vivo suchactivation would occur via immune complexed antigen, which for examplecould be an infectious agent, or in the cause of an autoimmune orallergic reaction could be an anutoimmune antigen or allergen.

The ATP-dependent luminescence assay was used to examine if BCRactivation-mediated viability of primary human B cells could besuppressed by an anti-CD19 antibody having enhanced Fc affinity forFcγRIIb. The above experiment was repeated, except that antibody serialdilutions of WT, variant, and control antibodies were performed intriplicate in 96-well microtiter plates containing RPMI1640 with 10%FBS, plus anti-CD79b at 1 μg/ml to stimulate BCR. The results are shownin FIG. 16. Again, B cells possessed low viability in the absence of BCRcrosslinking, and addition of 10 μg/ml anti-CD79b antibody stimulatedsurvival by about 6-fold (cells alone vs. anti-CD79b).Anti-CD19-S267E/L328F, the variant with the highest FcγRIIb affinity,inhibited BCR-stimulated viability in a dose-dependent manner. Incontrast, control antibodies including anti-CD19-IgG1 (Fv control) andanti-RSV-S267E/L328F (Fc control) minimally suppressed viability. Toassess if this inhibitory effect required coengagement of CD19 andFcγRIIb, as opposed to simultaneous binding of each receptor bydifferent antibodies, the anti-CD19-S267E/L328F variant was compared toa combination of anti-CD19-IgG1 and anti-RSV-S267E/L328F controls atequal concentrations. The combination of these antibodies shouldsimultaneously bind to both CD19 and FcγRIIb but, unlikeanti-CD19-S267E/L328F, is unable to crosslink these receptors. As shownin FIG. 16, the combination failed to suppress BCR activation-inducedsurvival, indicating that coengagement of FcγRIIb and CD19 by a singlemolecule is required to inhibit BCR-mediated viability. Not all variantswere capable of inhibiting B cell activation. As demonstrated in FIG.17, variants with moderately increased affinity relative to WT IgG1(S267A, 408 nM, 3.6-fold relative to native IgG1) do not inhibit B cellactivation. In contrast, that data in FIG. 18 demonstrate that variantswith high affinity, here the weakest affinity being the S267E variant(71.9 nM, 20.4-fold relative to native IgG1), do indeed inhibitactivation. Together the results in FIGS. 18, 19, and 20 suggest that acertain high affinity for FcγRIIb, about 100 nM, is needed to mediateinhibitory activity upon coengagement of FcγRIIb and BCR co-receptortarget antigen.

Example 4 Immunoglobulins Inhibit BCR Activation of Calcium Mobilizationin Primary Human B Cells Via Coengagement of FcγRIIb and CD19

Signals through the B-cell receptor complex ultimately result in calciumrelease, and this pathway can be inhibited by FcγRIIb (Nielsen et al.,2005, Transfus Med Hemother 32:339-347, incorporated entirely byreference). Intracellular calcium mobilization was used as aquantitative measure of BCR-mediated B cell activation to furtherevaluate the impact of the immunoglobulins. The current study usedprimary B cells from normal human donors as a more physiologicallyrelevant model of calcium signaling. In addition, rather thanstimulating primarily naive B cells via an anti-IgM antibody, ananti-human CD79b (Igβ) antibody was used in order to induce BCRactivation in both naive and memory B cells.

Intracellular free calcium concentration ([Ca2+]) was measured by flowcytometry using a Fluo-4 NW calcium assay (Molecular Probes, Eugene,Oreg.). Purified human B cells were resuspended at 5×105 cells/ml incalcium assay buffer and pre-loaded with Fluo-4 dye for 30 min at roomtemperature. After incubation with anti-CD19 or Fc and Fv controlantibodies, cells were stimulated by addition of 10 μg/ml of anti-CD79bantibody. Calcium flux kinetics was recorded using a FACSCanto II flowcytometer and data were analyzed using FlowJo software (Tree Star,Ashland, Oreg.).

Calcium mobilization in the presence of 10 μg/ml anti-CD19 native IgG1Fc antibody (α-CD19-native-IgG1) was increased relative to the vehiclecontrol (FIG. 19), as expected from coengagement of CD19 and BCR. Incontrast, IIbE variants of anti-CD19 IgG1 (also at 10 μg/ml) inhibitedcalcium mobilization induced by BCR crosslinking, with the twohighest-affinity variants showing greatest activity. To determine theimportance of CD19 binding for this effect, an Fc isotype controlantibody was used that binds with high affinity to FcγRIIb but not toCD19; this antibody, referred to as α-FITC-S267E/L328F in FIG. 19, hasthe S267E/L328F IgG1 heavy chain, but an Fv region that binds the haptenFITC (which is not on B cells). Relative to vehicle, this antibody hadminimal effect on calcium mobilization, indicating that CD19 binding isrequired to inhibit calcium mobilization. A dose-response extension ofthis experiment was carried out in which each point represents the areaunder the curve of a single calcium mobilization response as in FIG. 19.The data show that potency and efficacy of IIbE variants correlated withaffinity for FcγRIIb, consistent with the B cell viability assay, withanti-CD19-Native-IgG1 showing no dose response (FIG. 20). Therelationship between the EC50 of calcium inhibition and affinity forFcγRIIb is shown in FIG. 21.

To assess if the observed inhibition of calcium flux required engagementof both FcγRIIb and CD19 by a single antibody, a competition experimentwas performed. Because FcγRI has the highest affinity among all theFcγRs (FIG. 9) and competes with FcγRIIb for IgG binding (data notshown), a 24-fold molar excess soluble FcγRI (solFcγRI) to block theinteraction of the highest affinity antibody (α-CD19-S267E/L328F) withFcγRIIb (FIG. 22). BCR-induced calcium mobilization was againeffectively inhibited by 10 μg/ml α-CD19-S267E/L328F, but not byα-CD19-Native-IgG1. Notably, inhibition by the IIbE variant wascompletely abolished in the presence of soluble FcγRI, indicating thatFcγRIIb engagement is required. These results indicate that BCR-inducedcalcium mobilization can be inhibited by a single antibody that bindswith high affinity to both FcγRIIb and CD19 surface receptors.

Together the B cell viability and calcium mobilization results suggestthat Fc variant antibodies with high affinity for FcγRIIb may be usefulin methods for inhibiting activation of B cells. The data providedindicate that amino acid modification at positions 234, 235, 236, 237,239, 266, 267, 268, 325, 326, 327, 328, and 332 may be useful for suchinhibitory methods. In particular, the data provided indicate thatsubstitutions 234D, 234E, 234W, 235D, 235F, 235R, 235Y, 236D, 236N,237D, 237N, 239D, 239E, 266M, 267D, 267E, 268D, 268E, 327D, 327E, 328F,328W, 328Y, and I332E may be useful for such inhibitory methods.

Example 5 Immunoglobulins Induce SHIP Phosphorylation

SHIP activation is an FcγRIIb-dependent downstream component ofITIM-associated signaling. The capacity of the anti-CD19-S267E/L328Fantibody to stimulate SHIP phosphorylation (pSHIP) in the context of BCRactivation by anti-CD79b crosslinking antibody was assessed usingwestern analysis. Purified primary human B cells (1×107) were incubatedfor 10 min at 22° C. with 20 μg/ml anti-CD79b and 10 μg/ml anti-CD19antibodies, and then ice-cold PBS was added. For the positive control,10 μg/ml of anti-FcγRII-specific antibody (AT10) (AbD Serotec (Raleigh,N.C.) was used to crosslink FcγRIIb, and 20 μg/ml anti-mouse IgGFcγ-specific antibody was used to crosslink AT10 and anti-CD79b. Cellswere lysed in cold RIPA buffer (Cell Signaling, Beverly, Mass.)containing protease (Roche, Indianapolis, Ind.) and phosphatase(Calbiochem, San Diego, Calif.) inhibitor cocktails with 2 nMmicrocystin (Calbiochem), and incubated for 30 min on ice. Lysates werecentrifuged at 10,000 g for 30 min at 4° C. to remove debris,fractionated by SDS-PAGE (NuPAGE Novex, Invitrogen Life Technologies,Carlsbad, Calif.) and transferred to polyvinylidene difluoride membrane(Invitrogen Life Technologies). Western analysis was performed withphospho-SHIP (Cell Signaling Technologies, Beverly, Mass.) andGAPDH-specific primary antibodies (Biovision, Mountain View, Calif.)using HRP-conjugated anti-mouse IgG secondary antibody with enhancedchemiluminescence imaging (Amersham Bioscience, Newark, N.J.) and a UVPBioimaging image capturing system (Upland, Calif.).

The data are presented in FIG. 23. The western blot of cell extractsfrom purified primary human B cells showed that the anti-CD19 IIbEvariant stimulated a substantial increase in pSHIP level compared toanti-CD19 IgG1 and other controls (anti-RSV-S267E/L328F andanti-CD19-Fc-KO) (FIG. 23, lane 1 vs. lanes 2-4). As expected, directcrosslinking of FcγRIIb with BCR by anti-FcγRII antibody also showed anincrease in pSHIP level (lane 5). These results indicate thatsuppression of B cell function by the anti-CD19 IIbE antibody stimulatesSHIP phosphorylation, which is consistent with a known signaling pathwayof BCR-FcγRIIb coengagement.

Example 6 Immunoglobulins Inhibit BCR-dependent Anti-apoptotic Effect inPrimary Human B Cells

Although normal B cells in vivo have a long half life of approximately˜5 weeks, in vitro this lifespan is greatly reduced, with increasedapoptosis due to the lack of appropriate niche. B cell activation viastimulation via the BCR induces an anti-apoptotic effect and prolongsviability, as demonstrated in FIG. 15. In order to determine whether theantiproliferative activity of the IIbE variant was a result ofneutralizing BCR-mediated survival signals, thereby allowing in vitroapoptosis to proceed, an annexin-V staining assay was performed. 1×105purified primary human B cells were incubated for 24 h at 37° C. intriplicate with 1 μg/ml anti-CD79b and serial dilutions of anti-CD19 orcontrol antibodies in 100 μl RPMI1640 with 10% FBS. After incubation,cells were harvested and stained with PE-conjugated annexin-V(Biovision, Mountain View, Calif.) and 7-amino-actinomycin D (7-AAD,Invitrogen, Carlsbad, Calif.) at 5 μg/ml. Theannexin-V-positive/7-AAD-negative cells were acquired using a FACSCantoII flow cytometer, and analyzed with FACSDiva 5 analysis software (BDBiosciences).

The data are shown in FIG. 24. Annexin-V staining of primary human Bcells cultured in the presence or absence of anti-CD79b confirmed thatapoptosis was suppressed by BCR activation (FIG. 24, cells alone vs.anti-CD79b). This survival signal was neutralized in a dose-dependentmanner by anti-CD19-S267E/L328F, but not by anti-RSV-S267E/L328F Fccontrol or anti-CD19-IgG1 Fv control antibodies. Inhibition of theanti-apoptotic effect, like inhibition of calcium mobilization and cellproliferation, requires coengagement of CD19 and FcγRIIb by a singleantibody, because the combination of anti-CD19-IgG1 andanti-RSV-S267E/L328F (Fv and Fc controls, respectively) did notstimulate apoptosis. These data indicate that the anti-CD19 IIbE variantinhibits BCR-induced B cell proliferation by suppressing anti-apoptoticsurvival signals.

Example 7 Immunoglobulins do not Mediate Effector Functions

In order to evaluate the effect of modulating FcγRIIIa affinity, theimmunoglobulins were examined for their ADCC activity. Antibody serialdilutions were carried out in 96 well microtiter plates in triplicatesand incubated with Ramos target cells (10,000 total) to opsonize thetarget cells for ˜15 minutes. Ramos is an immortal huma B cell linederived from Burkitt's lymphoma cells. Purified NK cells (50,000 total)using negative selection kit from frozen PBMC prepared fromleukophoresis pack using standard Ficoll density gradient were added toappropriate concentration. The final working ADCC reaction was in 100 ulof 1% FBS/RPMI1640 for 4 hours at 37° C. after which, the amount of LDHreleased from the target cells was detected using fluorescent detectionsystem. The percentage of ADCC was determined by normalizing thebackground LDH activity (target and NK together without antibody)adjusted experimental LDH activity against the total LDH activitypresent in the target cells (spontaneous LDH activity present in thetarget cells alone adjusted TritonX100 lysed target cells). As shown inFIG. 25, many of the variants with enhanced FcγRIIb affinity, yet loweror equivalent FcγRIIIa affinity compared with wild-type IgG1, includingS267E, G236D/S267E, and S267E/L328F, lack ADCC activity. This isattributed to their reduced or ablated affinity for the activatingFcγRs, particularly FcγRIIIa which is the sole FcγR expressed on NKcells.

Immunoglobulins were also tested for their capacity to mediatephagocytosis by macrophages. Target cells were RS4; 11 cells, animmortal human B cell line derived from leukemia cells. Macrophagesexpress a variety of FcγRs, including FcγRI, FcγRIIa, FcγRIIb, andFcγRIIIa. Purified monocytes were differentiated in the presence ofmacrophage-colony stimulating factor for 5 days into macrophages.Macrophages were mixed with fluorescently labeled (PKH26) RS4; 11 cellsin 10% human AB serum in RPMI followed by the addition of anti-CD19antibodies and incubated for 4 hours at 37° C. APC conjugated antibodiesto CD14 and CD11 b were added to the cell mixture, washed and fixed.Phagocytosis was determined by the percentage CD14+CD11b+ and PKH26double positive population divided by the total number of stainedtumors. The data are shown in FIG. 26. Anti-CD19 IgG1 and the variantS239D/I332E demonstrated phagocytosis. In contrast, variants withenhanced FcγRIIb affinity yet reduced affinity for activating receptors,including S267E/L328F and G236D/S267E, had little or not phagocyticactivity, comparable to control antibody that targeted RSV.

Immunoglobulins were also tested for their capacity to mediate CDC.Release of Alamar Blue was used to monitor lysis of a target B cell lineby human serum complement. Raji cells (an immortal B cell line) werewashed in 10% FBS medium by centrifugation and resuspension, and loadedinto 96-well plates at 40,000 cells per well. Variant anti-CD19antibodies or Rituxan anti-CD20 control were added in ½ fold dilutionsto the indicated final concentrations. Human serum complement (Quidel)was diluted 1 to 5 with medium and added to antibody-opsonized targetcells. Plates were incubated for 2 hrs at 37° C., Alamar Blue was added,cells were cultured overnight, and fluorescence was measured. Data fromthis assay are shown in FIG. 27. In contrast to the anti-CD20 control,the variant anti-CD19 antibodies do not mediate CDC activity against Bcells.

Example 8 In Vivo Data Demonstrating Potential for Treating Autoimmuneor Inflammatory Disorder

A hallmark of autoimmunity in mouse and human is dysregulation ofFcγRIIb expression resulting in lower surface level of this inhibitoryreceptor, leading to an elevated level of B cell activation andconsequential failure of self-reactive B cell inhibition and productionof plasma cells secreting self-antigen specific immunoglobulins. Suchself-reactive immunoglobulin immune complexes are etiologic agents invarious organ failures in systemic autoimmunity and other arthriticinflammations such as systemic lupus erythematosus (SLE) and rheumatoidarthritis (RA. The immunoglobulins disclosed herein were assessed usinga huPBL-SCID mouse model as a proxy, by examining B cell activitymeasured by the number of B cells and plasma cell development bydetecting the antigen specific immunoglobulins. In this method, humanPBLs from normal or diseased (e.g., SLE or RA) donors are engrafted toimmune-deficient SCID mice and treated with the inhibitoryimmunoglobulin described herein, then challenged with an antigen toexamine the course of B cell development into plasma cells. In suchcase, the production of antigen-specific immunoglobulins is inhibitedfrom which can be inferred inhibition of both B cell activation anddifferentiation.

The protocol for this study is provided in FIG. 28A. Four differentgroups of mice with five mice in each group were engrafted with humanPBLs from a healthy donor. At day 16, test articles consisting of PBS(vehicle control), anti-CD19 with native IgG1 Fc (anti-CD19 IgG1 WT),anti-CD19 with IgG1 Fc of enhanced affinity for FcγRIIb (anti-CD19S267E/L328F) or Rituximab IgG1 anti-CD20 were given 10 mg/kg twiceweekly for a total of 6 doses. At day 24, antigen challenge with tetanustoxoid fragment C was given, and mice were sacrificed at days 31 and 38.Tetanus toxoid (TT) specific antibody production was examined. Theresults of this experiment are shown in FIG. 28B. The data shows thatbefore the antigen challenge, the level of anti-TT specific antibody wasvery low in all the groups. After immunization, the untreated PBScontrol group showed the highest level of anti-TT specific antibodylevel. In comparison, the B cell depleting anti-CD20 antibody producedlow level of antigen specific antibody level. After immunization, theanti-CD19 S267E/L328F group showed the lowest level of antigen specificantibodies, whereas the anti-CD19 IgG1 WT produced a higher level ofantigen specific antibody. These in vivo data show that the anti-CD19antibody with enhanced FcγRIIb affinity is capable of inhibiting B cellactivation and immunoglobulin secreting plasma cell differentiation, andthus support the potential of the immunoglobulins disclosed herein fortreating autoimmune and inflammatory disorders.

Example 9 Co-Engagement of FcγRIIb and Other Target Antigens

The use of antibodies to coengage CD19 and FcγRIIb is an example of howsimultaneous high affinity engagement of a B cell antigen and FcγRIIbmay be used to inhibit activation or proliferation of FcγRIIb+ cells. Asdiscussed above, FcγRIIb is a negative regulator of a number of celltypes, including but not limited to B cells, plasma cells, monocytes,macrophages, dendritic cells, neutrophils, basophils, eosinophils, andmast cells. A variety of antigens expressed on these FcγRIIb+ cell typesmay be also be co-targeted with high affinity FcγRIIb binding to inhibitcellular activation and/or proliferation. FIG. 29 provides a number ofexamples of antigens and cell types that may be targeted by theimmunoglobulins disclosed herein.

At the outset, it is not clear which antigens may serve as effectiveco-targets with FcγRIIb for modulation of cellular activity. A likelykey aspect of a potential co-target is its functional role in the cell,and in particular whether its intracellular signaling pathways (if any)overlap with those of FcγRIIb. CD19 is a co-receptor of the BCR complex,and thus the capacity of high affinity co-engagement of CD19 and FcγRIIbto inhibit B cell activation is likely related to the association ofCD19 with BCR and the negative regulatory role of FcγRIIb in inhibitingBCR-stimulated activation. Importantly, however, CD19 is not involved inantigen recognition, which is the specific function of the μ (IgM)component of the BCR. Rather CD19, and other proteins such as CD21,CD22, CD72, CD81, and Leu13, are BCR co-receptors. Of course, targetingof other components of the BCR, including the antigen recognition domain(μ, also referred to as IgM), and the signaling domains CD79a (Igα) andCD79b (Igβ), is also supported by the data herein. However, given thecomplex biochemical pathways involved in regulating cellular activationand proliferation of these cell types, evaluating which antigens (FIG.29) may serve as effective co-targets with FcγRIIb for modulation ofcellular activity requires experimentation.

In order to evaluate which antigens may be effective co-targets withFcγRIIb for modulating cellular activity, the S267E/L328F (high FcγRIIbaffinity) variant, along with WT IgG1 and Fc-KO variant(s) (^236R/L328Rand/or G236R/L328R) were cloned into antibodies specific for a varietyof other antigens expressed on FcγRIIb+ cells, including CD19, CD20,CD22, CD23, CD40, CD52, and CD79b. In several cases, multiple Fv'stargeting the same antigen were constructed in order to assess theepitope-dependence of the effects. FIG. 54A-FIG. 54D list the heavy andlight chain variable regions (VH and VL) of the antibodies used. The VHand VL genes targeting these antigens were constructed by genesynthesis, and variants were constructed, expressed, and purified asdescribed above.

The effect of high affinity co-engagement of these antigens with FcγRIIbwas evaluated using the ATP-dependent luminescence B cell viabilityassay as described above. FIGS. 30-35 show the results of theseexperiments. The data indicate that CD79b is also an effective co-targetfor using high affinity FcγRIIb co-engagement to inhibit B cellactivation. This is consistent with its role as the signaling componentof the BCR complex. Results using two additional anti-CD19 antibodiesagain confirmed the amenability of this antigen to controlling B cellactivation using high affinity FcγRIIb co-ligation, irrespective of thespecific epitope targeted. In contrast, no effect of high affinityFcγRIIb co-engagement was observed for antibodies with specificity forCD20, CD23, and CD52. Unexpectedly, dual targeting of FcγRIIb usingantibodies having specificity for CD22 and CD40 resulted in enhanced Bcell activation. In the case of CD22, this may be the result of its roleas a negative regulator of BCR activation. In the case of CD40, this maybe the result of its role as a positive regulator of B cell activationvia engagement at the T cell interface. It is known that some of theantibodies used are agonist, that is to say that their binding of CD40on B cells and other cells promotes positive signaling and activation ofB cells. In a sense these antibodies are mimicking the co-activationsignal of a T cell. The antibody (and thus epitope) dependence of thisactivation is likely related to the capacity of the antibodies toagonize. The reason for the enhanced agonism and stimulation of the Bcells upon high affinity (S267E/L328F) engagement of FcγRIIb, but notusing WT IgG1 or Fc-KO, is not currently clear, and requires furtherstudy.

Select antibodies targeting other antigens were tested further for theircapacity to inhibit intracellular calcium mobilization using the assaydescribed above. The results in FIG. 36 agree well with the data fromthe B cell viability assay. Whereas high affinity co-ligation of FcγRIIband CD23 had no effect on calcium mobilization, CD79b is an effectiveco-target for inhibition of calcium. High affinity FcγRIIb co-ligationwith CD22 and CD40 resulted in an increase in calcium mobilization,again consistent with the viability results.

In order to screen a larger set of antigens using commercial reagents, anovel method was developed for evaluating the capacity ofFcγRIIb/antigen co-engagement to inhibit of cellular activity. Thisapproach uses a haptenized version of an antibody or ligand that hasspecificity for the target antigen, together with variant versions of ananti-hapten antibody. This concept is illustrated in FIG. 37. A varietyof haptens are known in the art that may be used for this approach,including but not limited to FITC, biotin, and nitrophenyl.

The VH and VL genes of the anti-FITC antibody 4-4-20 were constructed bygene synthesis, and variants were constructed with enhanced affinity forFcγRIIb (S267E/L328F), along with WT IgG1 and FcγR knockout variant(s)(^236R/L328R and/or G236R/L328F). Antibodies were constructed, expressedand purified as described above. Commercial antibodies targetingantigens mu (μ), CD19, CD20, CD21, CD24, CD35, CD45RA, CD72, CD79a,CD79b, CD80, CD81, CD86, and HLA-DR were purchased from Beckman Coulter(Fullerton, Calif.), BD Pharmingen (San Jose, Calif.), AbD Serotec(Raleigh, N.C.), or GenTex, Inc. (San Antonio, Tex.). FITC labelingreagent (Pierce Biotech, Inc., Rockford, Ill.) was used to labelcommercial antibodies according to the supplied protocol at either roomtemperature or 37° C. for 1 hour. After labeling, un-reacted label wasremoved using BioSpin P-6 or P-30 columns from BioRad (Hercules, Calif.)and used with varying concentrations of anti-FITC antibodies inproliferation experiments as described above.

The effectiveness of the hapten approach for screening antigens wasfirst confirmed using anti-μ and anti-CD19 antibodies, two antigens thatare known to mediate inhibitory activity upon high affinityco-engagement with FcγRIIb. FIGS. 38 and 39 show anti-FITC antibodyvariants with high affinity for FcγRIIb, but not WT IgG1 or Fc-KOvariants, are able to inhibit B cell activation in the presence ofFITC-labeled anti-mu and anti-CD19 antibodies. These data are consistentwith the above approach wherein variants were incorporated directly intothe antibody with specificity for CD19 or mu, and thus confirm the useof the hapten approach for screening target antigens for capacity tomodulate cellular activity upon high affinity co-engagement withFcγRIIb.

FIGS. 40-52 show data from the ATP-dependent luminescence B cellviability using Fc variant versions of anti-FITC antibodies andantibodies targeting CD20, CD21, CD24, CD35, CD45RA, CD72, CD79a, CD79b,CD80, CD81, CD86, and HLA-DR. Inhibitory activity was observed fortargeting of CD79a and CD79b, consistent with their role in BCRsignaling. Targeting of CD81 and HLA-DR resulted in possible inhibition.The role of CD81 as a BCR co-receptor would seem to support the resultfor this antigen. The amenability of these antigens as co-targets forcontrolling cellular activation using high affinity FcγRIIb bindingrequires further study. Stimulatory activity was observed forco-targeting of CD72 with high affinity FcγRIIb affinity.

FIG. 53 provides a summary of the results from the target antigenscreening by both the Fc variant and hapten approaches. The dataindicate that immunoglobulins that coengage with high affinity bothFcγRIIb and μ, CD19, CD79a, Cd79b, CD81, and HLA-DR have potential forinhibiting the activation of FcγRIIb+ cells. The data also indicate thatimmunoglobulins that coengage with high affinity both FcγRIIb and CD22,CD40, and CD72 have potential for stimulating FcγRIIb+ cells. Overall,the results of this work suggest that simultaneous high affinityengagement of FcγRIIb and antigens involved or associated with the BCRcomplex, including μ, CD79a, CD79b, CD19, CD21, CD22, CD72, CD81, andLeu13, are methods for controlling the activation, proliferation, and/orviability of B cells.

All cited references are herein expressly incorporated by reference intheir entirety.

Whereas particular embodiments have been described above for purposes ofillustration, it will be appreciated by those skilled in the art thatnumerous variations of the details may be made without departing fromthe invention as described in the appended claims.

We claim:
 1. A protein comprising an Fc variant comprising at leastamino acid modifications G236N and S267E as compared to a human parentFc polypeptide, wherein numbering is according to the EU index accordingto Kabat.
 2. A pharmaceutical composition comprising protein accordingto claim 1, and a pharmaceutically acceptable carrier.
 3. A proteincomprising an Fc variant comprising at least amino acid modificationsG236N and S267E as compared to a human parent Fc polypeptide, whereinnumbering is according to the EU index according to Kabat, wherein saidprotein has increased binding affinity to FcγRIIb as compared to thehuman parent Fc polypeptide.